Update edit issuables button to bulk edit

What does this MR do and why?

• Updates Edit <issuable> button to Bulk edit
• Why?
  • The feature is called Bulk edit so this is more descriptive of what the button does
  • It shortens the button width

Screenshots or screen recordings

Example from project MRs, but the before/after is the same for epics, issues, and service desk issues (across both groups and projects if applicable)

Before	After

How to set up and validate locally

Affects the following:

• Project merge requests
• Group merge requests
• Project issues
• Group issues
• Service desk issues
• Epics

#398228 (closed)