fix: disable dynamic treatment of verbatim strings as YAML

[porridge]

It turns out there is another surprise layer of YAML unmashalling in this code, which only pops up if the value does look like valid YAML. 🤦🏻

The changed test case fails with the following diff (note the foo: bar crawling up to the parent level!). The associated code changes prevent this.

 apiVersion: v1
 data:
-  foo: true
   hba.conf: |-
     # PostgreSQL Client Authentication Configuration File
     local   all             all                                     scram-sha-256
   postgresql.conf: |
     hba_file = '/etc/stackrox.d/config/pg_hba.conf'
     foo = "bar"
 
     log_timezone = 'Etc/UTC' # comment
     more = false
+  yaml_looking_file: |-
+    foo: true
+    bar: baz
 kind: ConfigMap
 metadata:
   name: a-cm
   namespace: stackrox