Exit immediately if running minimal reproduction fails

What does this MR do and why?

This MR ensures that scripts/rspec_bisect_flaky (added in !75457 (merged)) exits immediately if running a minimal reproduction fails.

Previously, we've run specs for all combinations and continued if a combination failed.

This MR also fixes some shellcheck offenses.

Screenshots or screen recordings

Shellcheck offenses

$ shellckeck scripts/rspec_bisect_flaky

In scripts/rspec_bisect_flaky line 13:
files=( $@ )
        ^-- SC2206: Quote to prevent word splitting/globbing, or split robustly with mapfile or read -a.


In scripts/rspec_bisect_flaky line 25:
  bin/rspec $file $target
            ^---^ SC2086: Double quote to prevent globbing and word splitting.
                  ^-----^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean: 
  bin/rspec "$file" "$target"


In scripts/rspec_bisect_flaky line 29:
bin/rspec --bisect=verbose $@
                           ^-- SC2068: Double quote array expansions to avoid re-splitting elements.

For more information:
  https://www.shellcheck.net/wiki/SC2068 -- Double quote array expansions to ...
  https://www.shellcheck.net/wiki/SC2206 -- Quote to prevent word splitting/g...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...

How to set up and validate locally

While trying to reproduce failures from #351431 (closed) I ran

$ scripts/rspec_bisect_flaky ee/spec/features/protected_branches_spec.rb ee/spec/features/groups/analytics/cycle_analytics/filters_and_data_spec.rb ee/spec/features/projects/pipelines/pipeline_spec.rb ee/spec/features/admin/subscriptions/admin_views_subscription_spec.rb ee/spec/features/ci_shared_runner_warnings_spec.rb ee/spec/features/issues/epic_in_issue_sidebar_spec.rb ee/spec/features/boards/boards_spec.rb ee/spec/features/admin/admin_dev_ops_reports_spec.rb ee/spec/features/projects/audit_events_spec.rb ee/spec/features/projects/mirror_spec.rb ee/spec/features/namespace_user_cap_reached_alert_spec.rb ee/spec/features/registrations/user_sees_new_onboarding_flow_spec.rb ee/spec/features/groups/seat_usage/seat_usage_spec.rb ee/spec/features/admin/licenses/show_user_count_threshold_spec.rb ee/spec/features/projects/members/invite_group_and_members_spec.rb ee/spec/features/groups/iterations/user_views_iteration_spec.rb ee/spec/features/epics/filtered_search/visual_tokens_spec.rb ee/spec/features/admin/admin_credentials_inventory_spec.rb ee/spec/features/groups/iterations/user_edits_iteration_spec.rb ee/spec/features/merge_request/user_sets_approval_rules_spec.rb ee/spec/features/ide/user_commits_changes_spec.rb ee/spec/features/groups/billing_spec.rb ee/spec/features/issues/issue_actions_spec.rb ee/spec/features/admin/groups/admin_changes_plan_spec.rb ee/spec/features/projects/insights_spec.rb ee/spec/features/projects/feature_flags/feature_flag_issues_spec.rb ee/spec/features/merge_requests/user_views_all_merge_requests_spec.rb ee/spec/features/groups/analytics/ci_cd_analytics_spec.rb ee/spec/features/projects/integrations/user_activates_jira_spec.rb ee/spec/features/registrations/combined_registration_spec.rb ee/spec/features/projects/quality/test_case_create_spec.rb ee/spec/features/admin/admin_interacts_with_push_rules_spec.rb ee/spec/features/groups/security/compliance_dashboards_spec.rb ee/spec/features/groups/iterations/user_edits_iteration_cadence_spec.rb ee/spec/features/dashboards/activity_spec.rb ee/spec/features/projects_spec.rb ee/spec/features/projects/feature_flags/user_deletes_feature_flag_spec.rb ee/spec/features/groups/new_spec.rb

I was surprised to see that the script kept running if after first failures appeared.

MR acceptance checklist

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