* facade: Trim parsed args if overallocated

On parsing new command, if cap > 2* prev size needed, then trim command
to avoid holding onto oversized capacity. Also do this only over 256 KiB
to not churn on small commands and only correct large allocs

Signed-off-by: Abhijat Malviya <abhijat@dragonflydb.io>
(cherry picked from commit 0a369ac97018fec15313b54236e1ff89dc08cc6e)

* facade: Do not use clear to drop memory

This API has changed in recent versions of absl and no longer
deallocates

Signed-off-by: Abhijat Malviya <abhijat@dragonflydb.io>
(cherry picked from commit c062d4010f0a7ee4334be4cebe391ebd62358827)

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Signed-off-by: Abhijat Malviya <abhijat@dragonflydb.io>