[chore] Make check-contrib rebuild and reapply tools (open-telemetr…

…y#11670)

#### Description

There have been issues where changes in `mdatagen` are not properly
tested in CI and end up breaking collector-contrib (cf. open-telemetry#11167). This is
because `make check-contrib` does not rebuild or rerun `mdatagen` before
running contrib tests. This PR fixes that.

I added a flag to disable this when running manually, as it adds
significant time (~3 min!) to the run and is only really useful when
`mdatagen` has been modified.

I had to change the `make gotidy` to `make for-all CMD="go mod tidy"`
because we don't have a way to run `generate` on a specific module group
(and doing so may cause false-positives/negatives if a module group
depends on the generated files of another).

#### Link to tracking issue
Fixes open-telemetry#11167

Makefile

@@ -263,19 +263,30 @@ check-contrib:
 	@echo Setting contrib at $(CONTRIB_PATH) to use this core checkout
 	@$(MAKE) -C $(CONTRIB_PATH) for-all CMD="$(GOCMD) mod edit \
 		$(addprefix -replace ,$(join $(ALL_MOD_PATHS:%=go.opentelemetry.io/collector%=),$(ALL_MOD_PATHS:%=$(CURDIR)%)))"
-	@$(MAKE) -C $(CONTRIB_PATH) gotidy
+	@$(MAKE) -C $(CONTRIB_PATH) for-all CMD="$(GOCMD) mod tidy"
+
+	@$(MAKE) generate-contrib
+
+	@echo -e "\nRunning tests"
 	@$(MAKE) -C $(CONTRIB_PATH) gotest
+
 	@if [ -z "$(SKIP_RESTORE_CONTRIB)" ]; then \
 		$(MAKE) restore-contrib; \
 	fi
 
+.PHONY: generate-contrib
+generate-contrib:
+	@echo -e "\nGenerating files in contrib"
+	$(MAKE) -C $(CONTRIB_PATH) -B install-tools
+	$(MAKE) -C $(CONTRIB_PATH) generate GROUP=all
+
 # Restores contrib to its original state after running check-contrib.
 .PHONY: restore-contrib
 restore-contrib:
-	@echo Restoring contrib at $(CONTRIB_PATH) to its original state
+	@echo -e "\nRestoring contrib at $(CONTRIB_PATH) to its original state"
 	@$(MAKE) -C $(CONTRIB_PATH) for-all CMD="$(GOCMD) mod edit \
 		$(addprefix -dropreplace ,$(ALL_MOD_PATHS:%=go.opentelemetry.io/collector%))"
-	@$(MAKE) -C $(CONTRIB_PATH) -j2 gotidy
+	@$(MAKE) -C $(CONTRIB_PATH) for-all CMD="$(GOCMD) mod tidy"
 
 # List of directories where certificates are stored for unit tests.
 CERT_DIRS := localhost|""|config/configgrpc/testdata \