[chore][cmd/oteltestbedcol] Skip linting generated code (open-telemet…

…ry#27884)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
Same idea as open-telemetry#27865, remove generated code from being linted. The linter
is taking longer and longer to run as more components and dependencies
are added. This change is to remove unnecessary modules from being
linted, which will help reduce runtime and resources required.

**Link to tracking Issue:** <Issue number if applicable>
Related open-telemetry#27850

.golangci.yml

@@ -20,6 +20,7 @@ run:
  - third_party
  - local
  - cmd/otelcontribcol
+ - cmd/oteltestbedcol
 
  # default is true. Enables skipping of directories:
  # vendor$, third_party$, testdata$, examples$, Godeps$, builtin$