Replace 'JIRA' with 'Jira'

Gemfile

app/models/project_services/jira_service.rb

changelogs/unreleased/63479-jira-capitalization.yml

config/gitlab.yml.example

config/initializers/jira.rb

doc/README.md

doc/administration/logs.md

doc/api/merge_requests.md

doc/api/services.md

doc/integration/README.md

doc/push_rules/push_rules.md

doc/university/README.md

doc/university/support/README.md

doc/user/index.md

doc/user/project/integrations/jira.md

doc/user/project/integrations/jira_cloud_configuration.md

doc/user/project/integrations/jira_server_configuration.md

doc/user/project/integrations/project_services.md

lib/api/helpers/services_helpers.rb

locale/ar_SA/gitlab.po