Add exec connection options to remaining kubedb resource descriptors

[ArnobKumarSaha]

Adds spec.exec to 26 kubedb ResourceDescriptors, following the shape already used by mongodbs/postgreses/mysqls, so the UI can open an authenticated shell into the primary container.

Every kubedb RD now has spec.exec except etcds (see below).

How the values were derived

• Container name — *ContainerName constants in kubedb.dev/apimachinery/apis/kubedb/constants.go. Verified for all 26.
• Auth env vars — same constants file, or each operator's petset builder.
• serviceNameTemplate — uniformly {{- .metadata.name -}}; every DB's ServiceName() resolves to OffshootName().

Notes

• HTTP-only DBs (druid, milvus, qdrant, solr, weaviate) drop into bash with a curl one-liner in help, matching the existing elasticsearch pattern.
• neo4j reads credentials from the mounted /config/neo4j-auth/{username,password} files rather than env — NEO4J_USERNAME/NEO4J_PASSWORD are exported only inside the startup script (neo4j/pkg/controller/config.go:334-335), so they are not present in a fresh exec shell.
• aerospike's container sets no env vars at all (aerospike/pkg/controller/petset.go:149-156), so asadm runs bare.
• mssql prepends both /opt/mssql-tools18/bin and /opt/mssql-tools/bin to PATH, because the sqlcmd location depends on whether the version is >= 2022-cu14 (mssqlserver/pkg/controller/petset.go:507-511).
• etcd is excluded — there is no etcd operator repo under kubedb.dev/ and no EtcdContainerName constant, so the container name could not be verified.

Worth a reviewer's eye

Container names and env vars are grep-verified. The CLI binary names are not for a subset — these follow upstream convention rather than anything in the operator code: cqlsh, clickhouse-client, hdbsql, zkCli.sh, kafka-topics.sh, hz-cli, control.sh, asadm, and psql for pgbouncer/pgpool. Operator code did confirm memsql, rabbitmqctl, sqlplus, sqlcmd, db2, and psql (documentdb).

Testing

• go build ./... passes
• cmd/resource-fmt produces no further changes
• cmd/check-edge-label and cmd/check-embed pass
• cmd/check-schema fails, but fails identically on clean master and is not wired into the fmt or ci targets

Unrelated observations

• cmd/gen-resourcedescritors builds a fresh ResourceDescriptor with only Spec.Resource set and os.WriteFiles over the target without reading it (main.go:95-129), so re-running it would wipe spec.exec from every DB — including the ones that already had it before this PR.
• v1/memcacheds.yaml has a pre-existing exec entry with no container and no help. Left untouched.