Fix syntax error in ECS policy doc

[izaaklauer]

Closes #4872

Fixes a json syntax error in the ecs inline policy introduced in #4840 by adding a close quote

How can I verify this fix?

Run a waypoint install against an AWS account without a role named waypoint-runner, and verify success:

$ ./waypoint runner install   -platform=ecs   -server-addr=api.hashicorp.cloud:443   -ecs-runner-image=hashicorp/waypoint -ecs-region=us-east-1 -ecs-cluster=waypoint
✓ Finished connecting to: api.hashicorp.cloud:443
✓ Runner "01H7BA4XNXE0Y4CEMEHKFQAK3R" installed successfully to ecs
✓ Runner profile "ecs-01H7BA4XNXE0Y4CEMEHKFQAK3R" created successfully.
✓ Networking setup
✓ EFS ready
✓ Found existing IAM role to use: waypoint-runner-execution-role
✓ Created IAM task role: waypoint-runner
✓ Using existing log group
✓ Runner service created
✓ Runner "01H7BA4XNXE0Y4CEMEHKFQAK3R" adopted successfully.

[izaaklauer]

Integration tests are failing, but it seems to be transient, and we've observed this happen on other branches before and then pass on main.

Going to try merging for now. If it fails on main, we'll deal with that in a moment.