pgsql: Suppress length of Notice/Error msgs in PQtrace regress mode

Suppress length of Notice/Error msgs in PQtrace regress mode

A (relatively minor) annoyance of ErrorResponse/NoticeResponse messages
as printed by PQtrace() is that their length might vary when we move
error messages from one source file to another, one function to another,
or even when their location line numbers change number of digits.

To avoid having to adjust expected files for some tests, make the
regress mode of PQtrace() suppress the length word of NoticeResponse and
ErrorResponse messages.

Discussion: https://postgr.es/m/20210402023010.GA13563@alvherre.pgsql
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e7e341409a3d85aba4cf754ba9cf722a4d8e6676

Modified Files
--------------
src/interfaces/libpq/fe-trace.c | 11 ++++++++++-
src/test/modules/libpq_pipeline/traces/pipeline_abort.trace | 8 ++++----
src/test/modules/libpq_pipeline/traces/transaction.trace | 6 +++---
3 files changed, 17 insertions(+), 8 deletions(-)