[receiver/otlp] Rewrite logs related to server startup

[mx-psi]

The logs were a bit confusing when debugging DataDog/datadog-agent#13495, where an user was accidentally passing "0.0.0.0:4317" as an endpoint (quotes included). Making this a log field would make this issue more explicit.

[codecov]

Codecov Report

Base: 92.19% // Head: 92.19% // No change to project coverage 👍

Coverage data is based on head (fc56801) compared to base (7cb544d).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6174   +/-   ##
=======================================
  Coverage   92.19%   92.19%           
=======================================
  Files         219      219           
  Lines       13475    13475           
=======================================
  Hits        12423    12423           
  Misses        823      823           
  Partials      229      229           

Impacted Files	Coverage Δ
receiver/otlpreceiver/otlp.go	87.58% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[bogdandrutu]

Please rebase.