pgsql: Update our mapping of Windows time zone names some more.

Update our mapping of Windows time zone names some more.

Per discussion, let's just follow CLDR's default zone mappings
faithfully. There are two changes here that are clear improvements:

* Mapping "Greenwich Standard Time" to Atlantic/Reykjavik is actually
a better fit than using London, because Iceland hasn't observed DST
since 1968, so this is more nearly what people might expect.

* Since the "Samoa" zone is specified to be UTC+13:00, we must map
it to Pacific/Apia not Pacific/Samoa; the latter refers to American
Samoa which is now on the other side of the date line.

The rest of these changes look like they're choosing the most populous
IANA zone as representative. Whatever the details, we're just going
to say "if you don't like this mapping, complain to CLDR".

Discussion: https://postgr.es/m/3266414.1633045628@sss.pgh.pa.us

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/919c08d909f766bb51c5c617714364a91bb90d9d

Modified Files
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src/bin/initdb/findtimezone.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)