Remove lowercase normalization for `<name>` in `servlet.request.parameter.<name>`

[trask]

Comment says:

opentelemetry-java-instrumentation/instrumentation/servlet/servlet-common/library/src/main/java/io/opentelemetry/instrumentation/servlet/internal/ServletRequestParametersExtractor.java

Lines 75 to 77 in 9e8323a

	// normalize parameter name similarly as is done with header names when header values are
	// captured as span attributes
	parameterName = parameterName.toLowerCase(Locale.ROOT);

but headers are case insensitive, while request parameter are not, so we shouldn't be normalizing these.

This is currently behind experimental configuration otel.instrumentation.servlet.experimental.capture-request-parameters, so ok to change now, or could defer to 3.0.