fix: remove setting http.route in http span attributes

[mustafain117]

Which problem is this PR solving?

• resolves Remove http.route from http span attributes #2489

Short description of the changes

• In the http instrumentation, the http.route attribute is a duplicated field (with http.target attribute). This PR removes setting of http.route attribute for http spans
• This PR also adds a test to assert http.route is not set

[codecov]

Codecov Report

Merging #2494 (543b245) into main (33935e7) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2494      +/-   ##
==========================================
- Coverage   93.20%   93.20%   -0.01%     
==========================================
  Files         137      137              
  Lines        5017     5016       -1     
  Branches     1060     1059       -1     
==========================================
- Hits         4676     4675       -1     
  Misses        341      341              

Impacted Files	Coverage Δ
...es/opentelemetry-instrumentation-http/src/utils.ts	99.02% <0.00%> (-0.01%)	⬇️

[vmarchaud]

@mustafain117 you'll need to rebase the PR so we can merge it

[dyladan]

Looks good. Please fix the conflicts and this can merge.

[alolita]

+1