Have the Swiss abandoned neutrality?

To answer this question, we must understand what Swiss neutrality means. A first important distinction is between neutrality as a matter of international law, and neutrality as a tool of public policy:

Neutrality as a matter of international law is defined in the Hague Conventions (specifically Hague V and Hague XIII). That is, in international law, neutrality is about not participating or supporting warfare.

Neutrality as a policy tool is much more fluid. Notably, the Swiss constitution mentions it only in passing. Specifically, it is neither listed as an aim of the confederation:

Art. 2 Aims

1. The Swiss Confederation shall protect the liberty and rights of the people and safeguard the independence and security of the country.
2. It shall promote the common welfare, sustainable development, internal cohesion and cultural diversity of the country.
3. It shall ensure the greatest possible equality of opportunity among its citizens.
4. It is committed to the long term preservation of natural resources and to a just and peaceful international order

nor listed as a goal of its foreign policy:

Art. 54 Foreign relations

1. Foreign relations are the responsibility of the Confederation.
2. The Confederation shall ensure that the independence of Switzerland and its welfare is safeguarded; it shall in particular assist in the alleviation of need and poverty in the world and promote respect for human rights and democracy, the peaceful co-existence of peoples as well as the conservation of natural resources.
3. It shall respect the powers of the Cantons and protect their interests.

The only mention is this:

Art. 185 External and internal security

1. The Federal Council takes measures to safeguard external security, independence and neutrality of Switzerland.

basically putting the Federal Council in charge of this topic, which is apparently part of maintaining external security. This gives the Federal Council considerable leeway in defining what, exactly, neutrality means in any particular situation, as long as he respects the Hague Conventions, and pursues the goals quoted above.

In exercising this discretion, the Federal Council has deemed that its constitutional goals of "a just and peaceful international order", and "promoting respect for human rights and democracy and the peaceful co-existence of peoples" are better served by a different policy tool.

Or in the words of Ignazio Cassis, President of the Swiss Conferation and Federal Councillor of Foreign Affairs: (translation by me):

77 years after the end of World War 2, we are again witnessing war on our continent. Russia's attack against an independent European nation is an attack on sovereignty, an attack on liberty, an attack on democracy, an attack on civilians and the institutions of a free nation. This is unacceptable: Unacceptable under international law, unacceptable politically, and unacceptable morally. Accordingly, the Federal Council has decided to adopt the sanctions of the European Union in their entirety.

Why did we make this decision? Other democracies must be able to rely on Switzerland. Nations protecting international law must be able to rely on Switzerland. Nations upholding human rights must be able to rely on Switzerland. The Federal Council has considered the question of neutrality from this perspective. To play into the hands of an aggressor is not neutral. As signatory and depositary state of the Geneva convention, we have a responsibility to humanitarian law, and must not stand by while it is trampled underfoot.

This doesn't change Switzerland's willingness to actively contribute to a peaceful resolution of this conflict. But dialoque can only begin once the spiral of violence has been broken, and given way for a genuine will for peace talks. Ultimately, the sanctions support the goal of getting the Russian leadership to change its thinking.

To conclude, Switzerland has not "abandoned" its neutrality. It remains neutral in the legal sense, and continues to wield neutrality as a tool to pursue its goals in the world. But just how this tool is used depends on the circumstances at hand.

Further Reading

If you'd like to read more about the varied history of Swiss neutrality, ranging from an extremely broad interpretation that blocked Switzerland from joining pretty much all international organizations (even the United Nations!) in the 1950s, to a very narrow interpretation that allowed pretty much unchecked trade with the axis powers in the 1940s, even violating the Hague Conventions, the article Neutralität im Historischen Lexikon der Schweiz is a good starting point. Sadly only available for those reading German, French, or Italian, or equipped with a good machine translation tool :-)