[parquet] Not following the spec for TIMESTAMP_MILLIS legacy converted types

[sergiimk]

Describe the bug

Parquet spec prescribes that for backward compatibility the legacy converted type TIMESTAMP_MILLIS should be interpreted as logical type TimestampType (isAdjustedToUTC = true, unit = MILLIS), but that's currently not the case.

To Reproduce

Read a modern Parquet file with schema:

message x {
  REQUIRED INT64 system_time (TIMESTAMP(MILLIS,true));
}

observe data type Timestamp(Millisecond, Some("UTC"))

Read an old Parquet file with schema:

message x {
  REQUIRED INT64 system_time (TIMESTAMP_MILLIS);
}

observe data type: Timestamp(Millisecond, None)

TIMESTAMP_MILLIS gets incorrectly interpreted as naive/local timestamp.

Expected behavior

Because spec prescribes that TIMESTAMP_MILLIS should be interpreted as TIMESTAMP(MILLIS,true) I expected to see a timestamp with UTC timezone.

Additional context

These lines seem to be the source of the problem

[tustvold]

label_issue.py automatically added labels {'parquet'} from #4309