pgsql: Remove unnecessary array object_classes[] in dependency.c

Remove unnecessary array object_classes[] in dependency.c

object_classes[] provided unnecessary indirection between catalog OIDs
and the enum ObjectClass when calling add_object_address(). This array
has been originally introduced in 30ec31604d5 and was useful because not
all relation OIDs were compile-time constants back then, which has not
been the case for a long time now for all the elements of ObjectClass.

This commit removes object_classes[], switching to the catalog OIDs
when calling add_object_address(). This shaves some code while saving
in maintenance because it was necessary to maintain the enum ObjectClass
and the array in sync when adding new object types.

Reported-by: Jeff Davis
Author: Jelte Fennema-Nio
Reviewed-by: Jian He, Michael Paquier
Discussion: https://postgr.es/m/CAGECzQT3caUbcCcszNewCCmMbCuyP7XNAm60J3ybd6PN5kH2Dw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ef5e2e90859a39efdd3a78e528c544b585295a78

Modified Files
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src/backend/catalog/dependency.c | 181 ++++++++++++++-------------------------
src/include/catalog/dependency.h | 4 +-
2 files changed, 63 insertions(+), 122 deletions(-)