fix(instance) changed to better wording for selecting all instances in project

[mas-who]

Done

• Updated wording in pagination control for bulk selecting all instances in a project
• Fixes #552

QA

1. Run the LXD-UI:
   • On the demo server via the link posted by @webteam-app below. This is only available for PRs created by collaborators of the repo. Ask @lorumic or @edlerd for access.
   • With a local copy of this branch, run as described here.
2. Perform the following QA steps:
   • On the instances page, select one instance and check the wording in the pagination control for selecting all instances
   • On the instances page, filter the instances first then perform the previous action.
   • In the snapshots tab for a single instance, select one snapshot and check wording in pagination control should say 'select all x snapshots in instance'

Screenshots

[webteam-app]

Demo starting at https://lxd-ui-558.demos.haus

[edlerd]

Looks good, well done :)