ci(sidecar): add deploy files for prod

[seaerchin]

NOTE: DO NOT MERGE, PENDING INFRA DEPLOY

Problem

This adds in the missing deployment files for our support ecs service on production. this is raised as a separate PR so we can go through these 2 files in excruciating detail. the base PR is #1269.

For reviewers, please help to crosscheck against what i did below for env vars + deployment workflow to make sure i haven't missed anything

Solution

• create a new task definition for support for deployment to production.
• update our existing deploy_prod workflow to have a step to deploy the support ecs service.

for verification, these are the steps that i took: task def

• copied over the existing support-task-def for staging to production
• thereafter, i deleted the secrets section and replaced it with the one for backend-task-def (sans DD_SERVICE/DD_TAGS, which are done via env on the task def)
• replaced remaining stg/staging references with prod/production; referenced backend-task-def for the correct version (short or long) deploy_prod
• copied over the existing deploy-support workflow
• updated values (simple replacement cos this is deterministic via pulumi)

Breaking Changes

• [ ] Yes - this PR contains breaking changes
  • Details ...
• [x] No - this PR is backwards compatible with ALL of the following feature flags in this doc - should be fully back-compat, this should consume form webhook just fine

Tests

See base PR!

[seaerchin]

timestamp flaky