Use instrumentation loader to load plugins and instrumentations

[obecny]

Which problem is this PR solving?

• Fixes Use instrumentation loader to load plugins and instrumentations #1760

Short description of the changes

1. Removes PluginLoader from @opentelemetry/node
2. Replaces all usage of plugins configurations with instrumentation loader (examples, docs etc.) both for node and web
   using registerInstrumentations function

[codecov]

Codecov Report

Merging #1855 (611f3c3) into main (9981763) will increase coverage by 0.38%.
The diff coverage is 76.92%.

@@            Coverage Diff             @@
##             main    #1855      +/-   ##
==========================================
+ Coverage   92.37%   92.76%   +0.38%     
==========================================
  Files         167      173       +6     
  Lines        5522     5971     +449     
  Branches     1176     1269      +93     
==========================================
+ Hits         5101     5539     +438     
- Misses        421      432      +11     

Impacted Files	Coverage Δ
packages/opentelemetry-sdk-node/src/sdk.ts	73.68% <66.66%> (-0.23%)	⬇️
...kages/opentelemetry-node/src/NodeTracerProvider.ts	100.00% <100.00%> (ø)
...ackages/opentelemetry-web/src/WebTracerProvider.ts	100.00% <100.00%> (ø)
packages/opentelemetry-web/src/utils.ts	94.66% <0.00%> (ø)
...ntelemetry-web/src/enums/PerformanceTimingNames.ts	100.00% <0.00%> (ø)
packages/opentelemetry-web/src/types.ts	100.00% <0.00%> (ø)
...mentation-xml-http-request/src/enums/EventNames.ts	100.00% <0.00%> (ø)
...emetry-instrumentation-xml-http-request/src/xhr.ts	96.82% <0.00%> (ø)
...s/opentelemetry-instrumentation-fetch/src/fetch.ts	99.23% <0.00%> (ø)
... and 2 more

[vmarchaud]

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