Remove tools/code_check and update codecov

[chapulina]

See gazebo-tooling/action-gz-ci#32 and gazebo-tooling/release-tools#446

[codecov]

Codecov Report

Merging #246 (a5cb1de) into ign-transport8 (2bbb2af) will increase coverage by 0.35%.
The diff coverage is 89.83%.

@@                Coverage Diff                 @@
##           ign-transport8     #246      +/-   ##
==================================================
+ Coverage           83.41%   83.76%   +0.35%     
==================================================
  Files                  49       51       +2     
  Lines                4920     5033     +113     
==================================================
+ Hits                 4104     4216     +112     
- Misses                816      817       +1     

Impacted Files	Coverage Δ
log/src/Descriptor.cc	89.65% <ø> (ø)
log/src/cmd/LogCommandAPI.cc	62.50% <ø> (ø)
src/NodePrivate.hh	100.00% <ø> (ø)
src/NodeSharedPrivate.hh	100.00% <ø> (ø)
src/TopicStatistics.cc	88.52% <88.52%> (ø)
src/NodeShared.cc	78.89% <90.62%> (+0.94%)	⬆️
src/Node.cc	92.34% <92.59%> (-0.01%)	⬇️
include/ignition/transport/Discovery.hh	87.73% <100.00%> (+0.02%)	⬆️
include/ignition/transport/TopicStatistics.hh	100.00% <100.00%> (ø)
... and 4 more

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