test(net-http): improve instrumentation coverage

[mateenali66]

adds targeted unit tests for net_http helper and instrumentation config paths to improve coverage.

what's included:

• new tests for HttpHelper method normalization, unknown methods, and url.template span naming
• new tests for semconv selection (stable, dup, old) and split_path_and_query
• no workflow override changes, i could not find a net_http specific override in the current workflows

refs #2160

[thompson-tomo]

@mateenali66 thanks for this, the Workflow override is yet to have been merged into main. We will review and come back to you.

[mateenali66]

sounds good, no rush. once the workflow override is merged i can pick up the remaining coverage issues too (httpx etc).

[thompson-tomo]

@mateenali66 could you take a look at the CI error:

/home/runner/work/opentelemetry-ruby-contrib/opentelemetry-ruby-contrib/instrumentation/net_http/test/opentelemetry/instrumentation/net/http/http_helper_test.rb:9:in 'Kernel#require_relative': cannot load such file -- /home/runner/work/opentelemetry-ruby-contrib/opentelemetry-ruby-contrib/instrumentation/lib/opentelemetry/instrumentation/net/http/http_helper (LoadError)

And also remove the extra new line from the end of both files to fix that ci issue.

[mateenali66]

@thompson-tomo fixed both, require_relative paths corrected and trailing blank lines removed. also added missing sign-off on the second commit.