test: Update to latest stable Alpine release (3.19)

Alpine 3.11 has been EOL since 2021-11-01 and there's no
incompatibilities with the 3.19 version. The only fix needed is to use
the latest stable Gerrit 3.5 release in order to pick up some SSHD
fixes.

Change-Id: I4212a714af2c5ac5556d479139bf2097d9f0952b

test/docker/gerrit/Dockerfile

diff --git a/test/docker/gerrit/Dockerfile b/test/docker/gerrit/Dockerfile
index e9c40bf..1e4c3c6 100755
--- a/test/docker/gerrit/Dockerfile
+++ b/test/docker/gerrit/Dockerfile
@@ -1,4 +1,4 @@
-FROM gerritcodereview/gerrit:3.5.0.1-ubuntu20
+FROM gerritcodereview/gerrit:3.5.6-ubuntu20
 
 ENV GERRIT_SITE /var/gerrit
 COPY artifacts/plugins/ $GERRIT_SITE/plugins/

test/docker/run_tests/Dockerfile

diff --git a/test/docker/run_tests/Dockerfile b/test/docker/run_tests/Dockerfile
index 6e8e825..286fea2 100755
--- a/test/docker/run_tests/Dockerfile
+++ b/test/docker/run_tests/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.11
+FROM alpine:3.19
 
 ARG UID=1000
 ARG GID=1000