Allow Sync for non-root containers-hotreload example

[ibidani]

When deploying the hot-reload example to non-root containers, skaffold dev sync functionality fails with "permissions denied"
There has been multiple open issues referring to this error: #2041 #1950
This change will ensure examples will be compatible with more clusters with higher security requirements.

Description
chowning the target folder with the proper runtime UID so that tar xmf (Sync) command will not fail

User facing changes

Write n/a if not output or log lines changed and no behavior is changed

Before
The following error cases the Sync on save to break

WARN[0024] Skipping deploy due to sync error: copying files: Running [kubectl --context <context> exec node-56846577b4-c878r --namespace <namespace> -c node -i -- tar xmf - -C / --no-same-owner]
 - stdout: 
 - stderr: tar: removing leading '/' from member names
tar: can't remove old file app/index.js: Permission denied
command terminated with exit code 1
: exit status 1 

After
skaffold dev sync is working as expected on both node and python examples

Next PRs.

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes unit tests
• Mentions any output changes.
• Adds documentation as needed: user docs, YAML reference, CLI reference.
• Adds integration tests if needed.

Reviewer Notes

Release Notes

• hot-reload example skaffold dev sync working on non-root containers

[codecov]

Codecov Report

Merging #3680 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

Impacted Files	Coverage Δ
...affold/kubernetes/portforward/kubectl_forwarder.go	65.85% <0%> (-2.44%)	⬇️

[dgageot]

I just realized those changes should be made in integration/examples/hot-reload too. Otherzise, next time we do a release, your changes will be lost.

[ibidani]

Oops, I'll update the integration files today

[ibidani]

I updated the integration files
Thanks @dgageot

[dgageot]

@ibidani I've thought about your PR some more. And I wonder if you shouldn't be using COPY --chown instead, like in https://github.com/GoogleContainerTools/skaffold/blob/master/examples/nodejs/backend/Dockerfile. wdyt?

[ibidani]

Thanks Good suggestion, I'll update the code tonight

[ibidani]

@dgageot I just realized this PR inspired you to open #3683 which fixes this issue.
Should I close this PR?

[dgageot]

I don’t think so. I’d love to see all our examples better represent real projects. I didn’t want to step on your feet and changed a different sample.

[ibidani]

I've backported the great changes in #3683 into hot-reload example, per my tests on unprivileged cluster securityContext was necessary for the hot-load to succeed without the "tar: can't remove old file app/index.js: Permission denied" error mentioned above.
I've learned so much, thanks @dgageot

securityContext:
    runAsUser: 1000