Fix "missing continuation record" after standby promotion

Fix "missing continuation record" after standby promotion

Invalidate abortedRecPtr and missingContrecPtr after a missing
continuation record is successfully skipped on a standby. This fixes a
PANIC caused when a recently promoted standby attempts to write an
OVERWRITE_RECORD with an LSN of the previously read aborted record.

Backpatch to 10 (all stable versions).

Author: Sami Imseih <[email protected]>
Reviewed-by: Kyotaro Horiguchi <[email protected]>
Reviewed-by: Álvaro Herrera <[email protected]>
Discussion: https://postgr.es/m/44D259DE-7542-49C4-8A52-2AB01534DCA9@amazon.com