Fix GUC_NO_SHOW_ALL test scenario in 003_check_guc.pl

Applying: Add new GUC test checking that DISALLOW_IN_FILE => NOT_IN_SAMPLE
Using index info to reconstruct a base tree...
M	src/backend/utils/misc/guc_tables.c
M	src/test/regress/expected/guc.out
M	src/test/regress/sql/guc.sql
Falling back to patching base and 3-way merge...
Auto-merging src/test/regress/sql/guc.sql
Auto-merging src/test/regress/expected/guc.out
Auto-merging src/backend/utils/misc/guc_tables.c
CONFLICT (content): Merge conflict in src/backend/utils/misc/guc_tables.c
Patch failed at 0001 Add new GUC test checking that DISALLOW_IN_FILE => NOT_IN_SAMPLE

error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config advice.mergeConflict false"