ref(log): send logs by default when logs feature flag is enabled

[lcian]

Description

Removes the double opt-in for the log crate integration, as we'll now map to both an exception/breadcrumb and a log when the logs feature flag is active and the level is at or above INFO.

If the user has set enable_logs: false in their client options, the log will be created but dropped when it reaches the client.
This creates the log uselessly to later discard it. Still, in 99% of cases, if I use the logs feature flag, it means I want to get logs, so most probably enable_logs == true and the log is actually used.

This change is analogous to the one we already did for the tracing integration.

Issues

Closes #909
Closes RUST-112

[linear]

RUST-112 Enable logs by default in `log` integration

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.51%. Comparing base (3b78cf8) to head (af75932).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #915      +/-   ##
==========================================
+ Coverage   73.48%   73.51%   +0.02%     
==========================================
  Files          64       64              
  Lines        7533     7533              
==========================================
+ Hits         5536     5538       +2     
+ Misses       1997     1995       -2     

[szokeasaurusrex]

Looks good! Long term, I would consider completely removing the enable_logs flag, and have setting/unsetting the feature flag be the only way to enable/disable logs

[lcian]

@szokeasaurusrex Thanks. I also have this #910 which sets enable_logs to true if the feature flag is active, so practically you will only need the feature flag to get started.

[szokeasaurusrex]

@lcian Ah I was more referring to that we maybe should consider completely removing the flag, so that you cannot disable logs if the logs feature flag is turned on