Add an optional PodMonitor to the teleport-kube-agent chart

[thameezb]

Closes #30944

Adds in podmonitor to teleport-kube-agent helm chart

Linting passes
Newly added tests pass, existing tests fail locally

[hugoShaka]

@thameezb thank you for the high-quality contribution 🙌

Our current CI pipeline doesn't run on external contributions. To accept your commit, I created an internal PR here: #31169

I added a documentation commit as well.

[thameezb]

@thameezb thank you for the high-quality contribution 🙌

Our current CI pipeline doesn't run on external contributions. To accept your commit, I created an internal PR here: #31169

I added a documentation commit as well.

Awesome, much appreciated

Will close this one and track the buddy