feat(otel-node): restrict instrumentations to a list of known ones

[david-luna]

As discussed in a meeting EDOT should support only a list of known instrumentations. The decision was documented in #481 (comment)

We could limit the support foo names to just the known set of "already require(...)'d at top-level" instrumentations, and stop there. Then the implementation would be easy. This handles (1.).

That's exactly what this implementation does therefore the envvars OTEL_NODE_{DIS,EN}ABLE_INSTRUMENTATIONS refers only to the instrumentations included in EDOT. In sumary:

• The envvars refer to otel instrumentations via its short name
• The envars refer to the rest of included instrumentations (openai for now) via its full name

Closes #481

[david-luna]

mongoose tests failed twice: https://github.com/elastic/elastic-otel-node/actions/runs/13501299951/job/37727580220?pr=625

need to check if something works different in that specific node version (20.6.0)

[trentm]

nit: Thoughts on having these var names be otelInstrPrefix, otelInstrShortNames, etc. I.e. not the "SHOUTY_NAMES"? OTEL_INSTRUMENTATION_PREFIX is a constant, so I can see wanting to USE_THIS_STYLE, hence this is just a nit.

A small nice thing with not using OTEL_... is that we can (try to) limit any grep for OTEL_ to be about environment variables.