[Deprecation] Legacy Parser Hiera Functions (`hiera*`)

[silug]

Summary

Legacy parser functions hiera, hiera_array, hiera_hash, and hiera_include are already hard-failing shims and still carry stale deprecation text targeting Puppet 6.0.0 removal.

Evidence

• lib/puppet/parser/functions/hiera.rb:82 says removed in 6.0.0; implementation calls Error.is4x('hiera').
• lib/puppet/parser/functions/hiera_array.rb:70 says removed in 6.0.0; implementation calls Error.is4x('hiera_array').
• lib/puppet/parser/functions/hiera_hash.rb:80 says removed in 6.0.0; implementation calls Error.is4x('hiera_hash').
• lib/puppet/parser/functions/hiera_include.rb:81 says removed in Puppet 6.0.0; implementation calls Error.is4x('hiera_include').

Proposed OpenVox 9 Change

• Remove these parser function files and related loader registrations.
• Keep migration guidance in docs/changelog only (lookup and include(lookup(...))).

Compatibility / Risk

• Potential break for consumers depending on specific legacy error text.
• Functional behavior is already failure; removal should have minimal semantic impact.

Implementation Notes

• Validate no runtime requires still reference these files.
• Update tests to stop asserting legacy “removed in 6.0.0” strings.
• Update docs to remove stale references and keep modern lookup guidance.

Acceptance Criteria

• No lib/puppet/parser/functions/hiera*.rb compatibility stubs remain.
• Help/docs no longer include stale “removed in 6.0.0” messaging.
• Test suite passes with updated expected errors.

Suggested Tests

• Parser function load attempts confirm absent symbols or modern error path.
• Docs/reference generation does not emit legacy hiera* parser docs.

[binford2k]

Deprecated in 10e3796