pgsql: ci: Move execution method of tasks into yaml templates

ci: Move execution method of tasks into yaml templates

This is done in preparation for making the compute resources for CI
configurable. It also looks cleaner.

Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/20230808021541.7lbzdefvma7qmn3w@awork3.anarazel.de
Backpatch: 15-, where CI support was added

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/cad461b044b521c5f80d180194d6e27dce82c424

Modified Files
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.cirrus.yml | 85 +++++++++++++++++++++++++++++++++++++++++--------------------
1 file changed, 57 insertions(+), 28 deletions(-)