Annotation and label values containing a newline previously round-tripped
as two adjacent `key: value` lines, and the second line then failed the
`SplitN(line, ": ", 2)` parse on read. Move the per-`(processType,
resourceType)` files to `PropertyMap*` storage so `\n` in values and `/`
in keys are preserved verbatim. An idempotent `TriggerInstall` migration
walks `--global` and every app, converting any legacy line-formatted file
in place by probing `PropertyMapGet` first and rewriting via
`PropertyListGet` only when the probe fails. Property names are
unchanged, so the annotations/labels report scanner and the
`reservedAnnotationPrefixes` filter keep working without modification.
Closes#8719.
21ed5fb738