pgsql: doc: Remove event trigger firing matrix

doc: Remove event trigger firing matrix

This is difficult to maintain accurately, and it was probably already
somewhat incorrect, especially in the sql_drop and table_rewrite
categories.

The prior section already documented which DDL commands are *not*
supported (which was also slightly outdated), so let's expand that a
bit and just rely on that instead of listing out each command in full
detail.

Reviewed-by: Daniel Gustafsson <daniel(at)yesql(dot)se>
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Reviewed-by: Jian He <jian(dot)universality(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/CACJufxE_UAuxcM08BW5oVsg34v0cFWoEt8yBa5xSAoKLmL6LTQ%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a0be94067e76c81a2bbba6a98b584b870024e363

Modified Files
--------------
doc/src/sgml/event-trigger.sgml | 1028 +++-------------------------------
src/backend/commands/event_trigger.c | 4 +-
src/backend/tcop/utility.c | 3 +
3 files changed, 81 insertions(+), 954 deletions(-)