Bump Elasticsearch in CI to 7.10.1

We are planning on upgrading our production environment to 7.10.2 so we
want to use the same version in CI.

There isn't, yet, a 7.10.2 published to dockerhub. Elastic also has
their own registry where they released 7.10.2 but we've had problems
with being rate limited from this registry before
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/21750 so it's best
to just go with 7.10.1 in CI for now until it's published.

I did, however, confirm in CI that 7.10.2 does work with the Elastic
docker image
https://gitlab.com/gitlab-org/gitlab/-/commit/5597a647c1092af83c717a8269bafcfe770178d0
.

.gitlab/ci/global.gitlab-ci.yml

@@ -102,7 +102,7 @@
     - name: postgres:11.6
       command: ["postgres", "-c", "fsync=off", "-c", "synchronous_commit=off", "-c", "full_page_writes=off"]
     - name: redis:5.0-alpine
-    - name: elasticsearch:7.9.2
+    - name: elasticsearch:7.10.1
       command: ["elasticsearch", "-E", "discovery.type=single-node"]
   variables:
     POSTGRES_HOST_AUTH_METHOD: trust
@@ -113,7 +113,7 @@
     - name: postgres:12
       command: ["postgres", "-c", "fsync=off", "-c", "synchronous_commit=off", "-c", "full_page_writes=off"]
     - name: redis:5.0-alpine
-    - name: elasticsearch:7.9.2
+    - name: elasticsearch:7.10.1
       command: ["elasticsearch", "-E", "discovery.type=single-node"]
   variables:
     POSTGRES_HOST_AUTH_METHOD: trust