fix: remove component attribute from instrumentations

[blumamir]

Which problem is this PR solving?

• The "component" attribute was removed from semantic conventions back in Feb 2020, but some instrumentations were written before this change and still report this attribute.

Short description of the changes

• remove the "component" attribute from "@opentelemetry/instrumentation-document-load" and "@opentelemetry/instrumentation-long-task" as well as clean up some related dead code in other places

[codecov]

Codecov Report

Merging #1399 (4a6adcf) into main (ee0a59a) will decrease coverage by 0.03%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1399      +/-   ##
==========================================
- Coverage   96.08%   96.06%   -0.03%     
==========================================
  Files          14       14              
  Lines         895      890       -5     
  Branches      192      192              
==========================================
- Hits          860      855       -5     
  Misses         35       35              

Impacted Files	Coverage Δ
...entation-document-load/src/enums/AttributeNames.ts	100.00% <ø> (ø)
...strumentation-document-load/src/instrumentation.ts	98.79% <ø> (-0.02%)	⬇️
...y-instrumentation-long-task/src/instrumentation.ts	94.44% <ø> (-0.30%)	⬇️

[martinkuba]

Before merging this I want to double check that there is another way of identifying the document load spans. I don't think there are any semantic conventions specifically for the browser instrumentations (unlike the database one). Users might be relying on the component to be there for these spans.

[Flarna]

There is instrumentation scope on each span which identifies the tracer. Each instrumentation has a tracer so this should be an exact replacement

[martinkuba]

@Flarna That's a good point. I think it still might break some queries for some users, but this are experimental instrumentations, and as long as there is some way to identify I am 👍