[7.16] Fix ingest timezone parsing backport(#63876)

[pgomulka]

this commit aligns timezone parsing logic with DateFormat.Iso8601. Timezone can be provided on a pattern and as ingest parameter. When no timezone is provided on a pattern it is defaulted to UTC or an ingest parameter (if provided).

When timezone is not present in a pattern, but an ingest timezone parameter is provided - a date should be parsed as if it was in that timezone.
Example: pattern "uuuu-MM-dd'T'HH:mm", text "2020-01-01T01:00", timezone: -01:00 should return 2020-01-01T01:00:00-01:00
If the pattern has a timezone and a timezone parameter is provided - a date should parsed with a timezone from input, and then "recalculated" to an ingest parameter
Example "uuuu-MM-dd'T'HH:mm XXX", text "2020-01-01T01:00 -02:00", timezone -01:00 should return 2020-01-01T02:00:00-01:00
relates #38407
relates #51215
closes #63458

backports #63876

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[elasticmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[elasticmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[grcevski]

LGTM! Backport looks clean.