[Backport 2.6] Quote yugabyte gflag overrides

Summary:
In order to maintain compatibility with previous chart behavior, it's
necessary to quote gflag overrides in order to prevent breakages due to
multi-word gflag values.

This issue was introduced in 4e560f0

Test Plan:
Run template containing multi-word gflag value without this change:
$ helm install yugabyte ./ --set gflags.master.test1234="asdf asdf" --dry-run --debug
...
              --test1234=asdf asdf \
...

Run template contianing multi-word gflag value with this change:
$ helm install yugabyte ./ --set gflags.master.test1234="asdf asdf" --dry-run --debug
...
              --test1234="asdf asdf" \
...
Verify that the argument value is properly quoted.

Reviewers: sanketh

Reviewed By: sanketh

Subscribers: yugaware

Differential Revision: https://phabricator.dev.yugabyte.com/D12064

Author: jvigil-yugabyte

stable/yugabyte/templates/service.yaml

@@ -297,7 +297,7 @@ spec:
               --num_cpus={{ ceil $root.Values.resource.master.requests.cpu }} \
               --undefok=num_cpus,enable_ysql \
             {{- range $flag, $override := $root.Values.gflags.master }}
-              --{{ $flag }}={{ $override }} \
+              --{{ $flag }}={{ quote $override }} \
             {{- end }}
             {{- if $root.Values.tls.enabled }}
               --certs_dir=/opt/certs/yugabyte \
@@ -346,7 +346,7 @@ spec:
               --use_cassandra_authentication=true \
             {{- end }}
             {{- range $flag, $override := $root.Values.gflags.tserver }}
-              --{{ $flag }}={{ $override }} \
+              --{{ $flag }}={{ quote $override }} \
             {{- end }}
             {{- if $root.Values.tls.enabled }}
               --certs_dir=/opt/certs/yugabyte \