Placement manager hard-codes resource name

**Describe the bug**
The Placement Manager hard-codes the resource name to 'couchdb' in 'couchdb/ci/templates/placementmanager.yaml', line 37, of this chart and in '/app/src/couch/couch.py', line 166, of the placement manager code. This means that if you use Placement Manager and name your resource anything other than 'couchdb' deployment fails.

**Version of Helm and Kubernetes**:
Helm: version.BuildInfo{Version:"v3.14.3", GitCommit:"f03cc04caaa8f6d7c3e67cf918929150cf6f3f12", GitTreeState:"clean", GoVersion:"go1.22.1"}
Kubernetes: 1.28

**What happened**:
Deployment failed due to my naming the resource something other than 'couchdb'.

**What you expected to happen**:
I expected the chart to deploy Couch to k8s and spread the shards across availability zones.

**How to reproduce it** (as minimally and precisely as possible):
Call your resource anything other than 'couchdb' and try to deploy with the value 'placementConfig: enabled: true'.

**Anything else we need to know**: