Fido-mode: don't error if case-fold-search is globally nil

bug#67884

To prevent errors, the same case-fold-search setting used for
originally selecting the candidate should be used when scoring it.

* lisp/minibuffer.el (completion--flex-score): Fix
1 job for master in 5 minutes and 18 seconds (queued for 18 seconds)
Status Job ID Name Coverage
  Normal
failed #78628
test-lisp-inotify

00:05:18

 
Name Stage Failure
failed
test-lisp-inotify Normal
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
$ find ${test_name} -type d -depth -exec rmdir {} + 2>/dev/null
Uploading artifacts...
test-lisp-inotify-c0c79b0b/: found 119 matching files
Uploading artifacts to coordinator... ok
id=78628 responseStatus=201 Created token=Rmf_X7qc
Uploading artifacts...
test-lisp-inotify-c0c79b0b/junit-test-report.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=78628 responseStatus=201 Created token=Rmf_X7qc
ERROR: Job failed: exit code 2