ci: re-enable support for truffleruby on all but the GRPC exporter (#1428)

* ci: re-enable support for truffleruby on all but the GRPC exporter

We still cannot install the `grpc` gem with truffleruby, but the rest of
the otlp exporters build and pass tests. And, the GRPC version of the
exporter is currently experimental, unfinished, and unreleased anyways.

* chore: disable annoying rubocop rule

---------

Co-authored-by: Francis Bogsanyi <[email protected]>

Author: ahayworth

.github/workflows/ci.yml

@@ -142,9 +142,6 @@ jobs:
         shell: bash
         run: |
           echo "skip=false" >> $GITHUB_OUTPUT
-          [[ "${{ matrix.gem }}" == "opentelemetry-exporter-otlp"        ]] && echo "skip=true" >> $GITHUB_OUTPUT
-          [[ "${{ matrix.gem }}" == "opentelemetry-exporter-otlp-common" ]] && echo "skip=true" >> $GITHUB_OUTPUT
-          [[ "${{ matrix.gem }}" == "opentelemetry-exporter-otlp-http"   ]] && echo "skip=true" >> $GITHUB_OUTPUT
           [[ "${{ matrix.gem }}" == "opentelemetry-exporter-otlp-grpc"   ]] && echo "skip=true" >> $GITHUB_OUTPUT
           # This is essentially a bash script getting evaluated, so we need to return true or the whole job fails.
           true

test_helpers/.rubocop.yml

@@ -16,5 +16,7 @@ Naming/FileName:
     - "lib/opentelemetry-test-helpers.rb"
 Style/ModuleFunction:
   Enabled: false
+Gemspec/DevelopmentDependencies:
+  Enabled: false
 Gemspec/RequireMFA:
   Enabled: false