[Removal] Remove deprecated experimental semantic conventions (#1741)

[marcalff]

Fixes #1741

Changes

Remove deprecated files:

api/include/opentelemetry/trace/experimental_semantic_conventions.h
sdk/include/opentelemetry/sdk/resource/experimental_semantic_conventions.h

Remove deprecated global function:

  uint32_t hashCode(const char *str, uint32_t h = 0)

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[marcalff]

[DO NOT MERGE], for now.

First, #1744 should be merged and released with version N (Deprecation announcement)
Deprecation announced in 1.8.0

ON HOLD AGAIN: wait for 1.8.1 release first.
Then, #1743 should be merged and released with version N+1 (Removal)

[codecov]

Codecov Report

Merging #1743 (425cefb) into main (41821d6) will decrease coverage by 0.06%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1743      +/-   ##
==========================================
- Coverage   85.79%   85.73%   -0.05%     
==========================================
  Files         171      171              
  Lines        5240     5240              
==========================================
- Hits         4495     4492       -3     
- Misses        745      748       +3     

Impacted Files	Coverage Δ
api/include/opentelemetry/common/string_util.h	100.00% <ø> (ø)
ext/src/http/client/curl/http_client_curl.cc	80.31% <0.00%> (-1.13%)	⬇️

[lalitb]

LGTM

[esigo]

LGTM
Thanks for the PR :)