[kong] remove default securityContext

[rainest]

What this PR does / why we need it:

Removes the default security context (which ran the container as UID 1000). This does not appear to be necessary and removing it improves compatibility with OpenShift.

Which issue this PR fixes

• fixes Remove securityContext by default in the chart #137

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• PR is based off the current tip of the next branch and targets next, not master
• New or modified sections of values.yaml are documented in the README.md
• Title of the PR and commit headers start with chart name (e.g. [kong])

[hbagdi]

Upgrade guide should include a note for this (not in scope of this PR).

[rainest]

Shouldn't need it--there's no change in behavior with it gone, nor any harm leaving it in place if you already had it from an old values.yaml.