Don't call Thread#setContextClassLoader()

[mateuszrzeszutek]

Related to #7220

Unfortunately it doesn't fix the aforementioned issue; while the CL used is no longer the agent classloader, gauge collection still throws that error.
Still, I think this is a good change that removes one source of agent's CL leaking into application runtime.

[laurit]

opentelemetry-java-instrumentation/gradle-plugins/src/main/kotlin/io.opentelemetry.instrumentation.muzzle-check.gradle.kts

Lines 418 to 426 in 9e5d962

	fun withContextClassLoader(classLoader: ClassLoader, action: () -> Unit) {
	val currentClassLoader = Thread.currentThread().contextClassLoader
	Thread.currentThread().contextClassLoader = classLoader
	try {
	action()
	} finally {
	Thread.currentThread().contextClassLoader = currentClassLoader
	}
	}

shouldn't be needed after this

[trask]

I'm going to merge to include this in release, I'll send PR to follow-up on @laurit's latest suggestion