Remove deprecated code from ChapelArray and ChapelSyncVars

[DanilaFe]

Deprecations were introduced by the following PRs:

• Add deprecation warning for implicit initializers with sync/single/atomics  #22639
• Deprecate array->string cast #23380
• Add deprecation warning for implicit initializers with sync/single/atomics  #22639

Others predated the existence of @deprecated and even deprecated.

These occurred more than 6 months ago.

Failing tests:

[Error matching compiler output for deprecated/IO/array-string-cast]
[Error matching compiler output for deprecated/sync/default-init (compopts: 3)]
[Error matching compiler output for deprecated/sync/sync-casting]
[Error matching compiler output for deprecated/sync/sync-direct-access]
[Error matching compiler output for trivial/deitz/coerce-assign/plusassign_error]
[Error matching compiler output for types/imag/opequals2 (compopts: 1)]
[Error matching compiler output for types/imag/opequals2 (compopts: 2)]
[Error matching compiler output for types/sync/ferguson/sync-copy-init-cannot-coerce]
[Error matching compiler output for types/sync/ferguson/sync-copy-init-cannot-coerce2]
[Error matching compiler output for types/sync/ferguson/sync-copy-init-other-sync]
[Error matching compiler output for types/sync/initFromSync]

Testing

• paratest