Support Elasticsearch v9 (for v10.11) (#35925)

* Support Elasticsearch v9 alongside v8

* Add CI workflow changes for Elasticsearch v8/v9 testing

* Support Elasticsearch v7 in addition to v8/v9, add v7 CI test job

Lowers the minimum supported ES version from 8 to 7 to avoid dropping
v7 support in a dot release. Adds a dedicated CI job to verify v7
compatibility alongside the existing v8 and v9 (default) jobs.

* Fix ES7 plugin install crash on cgroup v2 hosts

* Fix ES 7 container startup on cgroup v2 Linux (GitHub Actions)

ES 7 bundles JDK 11, which crashes with a NullPointerException in
CgroupV2Subsystem.getMountPoint() on modern Linux kernels that use
cgroup v2 (including GitHub Actions ubuntu-latest runners). The flag
was already set during the Dockerfile RUN step, but not at runtime.

Adding -XX:-UseContainerSupport to ES_JAVA_OPTS in docker-compose
fixes the crash. The flag is harmless on ES 8/9 which ship JDK 17+
where the cgroup v2 bug is fixed (it simply opts out of container-aware
JVM sizing).

* Capture docker compose logs in CI test artifact

* Use ES 7.17.29 for v7 CI test; remove cgroup v2 workarounds

ES 7.17.0 bundled JDK 17.0.1 which had a cgroup v2 bug
(CgroupV2Subsystem NPE) not fixable via -XX:-UseContainerSupport.
ES 7.17.29 bundles JDK 22 where the bug is long fixed.

Reverts the -XX:-UseContainerSupport workarounds added in the
previous two commits as they were based on a wrong diagnosis
and are no longer needed.

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/Makefile

@@ -1,4 +1,4 @@
-.PHONY: build package run stop run-client run-server run-node run-haserver stop-haserver stop-client stop-server restart restart-server restart-client restart-haserver start-docker update-docker clean-dist clean nuke check-style check-client-style check-server-style check-unit-tests test dist run-client-tests setup-run-client-tests cleanup-run-client-tests test-client build-linux build-osx build-windows package-prep package-linux package-osx package-windows internal-test-web-client vet run-server-for-web-client-tests diff-config prepackaged-plugins prepackaged-binaries test-server test-server-ee test-server-quick test-server-race test-mmctl-unit test-mmctl-e2e test-mmctl test-mmctl-coverage mmctl-build mmctl-docs new-migration migrations-extract test-public mocks-public
+.PHONY: build package run stop run-client run-server run-node run-haserver stop-haserver stop-client stop-server restart restart-server restart-client restart-haserver start-docker update-docker clean-dist clean nuke check-style check-client-style check-server-style check-unit-tests test dist run-client-tests setup-run-client-tests cleanup-run-client-tests test-client build-linux build-osx build-windows package-prep package-linux package-osx package-windows internal-test-web-client vet run-server-for-web-client-tests diff-config prepackaged-plugins prepackaged-binaries test-server test-server-ee test-server-elasticsearch test-server-quick test-server-race test-mmctl-unit test-mmctl-e2e test-mmctl test-mmctl-coverage mmctl-build mmctl-docs new-migration migrations-extract test-public mocks-public
 
 ROOT := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
 
@@ -476,6 +476,15 @@ test-server-ee: check-prereqs-enterprise start-docker gotestsum ## Runs EE tests
 	@echo Running only EE tests
 	$(GOBIN)/gotestsum --packages="$(EE_PACKAGES)" -- $(GOFLAGS) -timeout=20m
 
+ES_PACKAGES=$(shell $(GO) list ./enterprise/elasticsearch/...)
+
+test-server-elasticsearch: export GOTESTSUM_FORMAT := $(GOTESTSUM_FORMAT)
+test-server-elasticsearch: export GOTESTSUM_JUNITFILE := $(GOTESTSUM_JUNITFILE)
+test-server-elasticsearch: export GOTESTSUM_JSONFILE := $(GOTESTSUM_JSONFILE)
+test-server-elasticsearch: check-prereqs-enterprise start-docker gotestsum ## Runs Elasticsearch tests.
+	@echo Running only Elasticsearch tests
+	$(GOBIN)/gotestsum --rerun-fails=3 --packages="$(ES_PACKAGES)" -- $(GOFLAGS) -timeout=20m
+
 test-server-quick: export GOTESTSUM_FORMAT := $(GOTESTSUM_FORMAT)
 test-server-quick: export GOTESTSUM_JUNITFILE := $(GOTESTSUM_JUNITFILE)
 test-server-quick: export GOTESTSUM_JSONFILE := $(GOTESTSUM_JSONFILE)