Fix inconsistent quoting for some options in TAP tests

Fix inconsistent quoting for some options in TAP tests

This commit addresses some inconsistencies with how the options of some
routines from PostgreSQL/Test/ are written, mainly for init() and
init_from_backup() in Cluster.pm.  These are written as unquoted, except
in the locations updated here.

Changes extracted from a larger patch by the same author.

Author: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Discussion: https://postgr.es/m/87jz8rzf3h.fsf@wibble.ilmari.org