update Trillian TLS configuration

[fghanmi]

Summary

This PR enhances the hostname extraction in the dial function. It ensures that if rpcServer contains a port, only the hostname is used for establishing a TLS connection. This prevents potential TLS connection failures caused by including the port in the ServerName field. The updates include:

• Extracting the hostname from rpcServer by removing the port if present.
• Using the extracted hostname in the TLS configuration to set the ServerName field.

root issue: #2163

These changes have been tested on a working sigstore stack, it managed to sign/verify container images.

Release Note

Documentation

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 51.42%. Comparing base (488eb97) to head (c9940d7).
Report is 177 commits behind head on main.

Files	Patch %	Lines
pkg/api/api.go	60.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2202       +/-   ##
===========================================
- Coverage   66.46%   51.42%   -15.04%     
===========================================
  Files          92      189       +97     
  Lines        9258    19465    +10207     
===========================================
+ Hits         6153    10010     +3857     
- Misses       2359     8378     +6019     
- Partials      746     1077      +331     

Flag	Coverage Δ
e2etests	50.23% <60.00%> (+2.67%)	⬆️
unittests	43.01% <0.00%> (-4.68%)	⬇️

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