Revert "Bug 1052241 - Disable network activity icon in DEBUG mode"

This reverts commit bcc84b7dcb3be974ca7a329f1aa63c9cfb1c4f91.

Conflicts:
	apps/system/js/statusbar.js
Bug 1063310 - [email] When sending multiple attachments, all but the first are sent as zero-byte attachments. r=asuth
Bug 1066793 - improved ambient notification indicator accessibility. r=alive
Merge pull request #24018 from yzen/bug-1066793

Bug 1066793 - improved ambient notification indicator accessibility.
Merge pull request #23976 from mcav/attachzero

Bug 1063310 - [email] When sending multiple attachments, all but the fir...
Bug 1065167 - [email] The contents of the outbox won't show until any active sending process completes due to held mutex by sending process. r=asuth
Bug 1063540 - Manual setup error message when IMAP and SMTP settings are wrong. r=asuth
Bug 1065632 - Reword FxA description in FTE flow. r=sfoster
Merge pull request #24065 from mcav/outbox-show-msgs

Bug 1063540 - Manual setup error message when IMAP and SMTP settings are... r=asuth
Merge pull request #24064 from mcav/mutex-release

Bug 1065167 - [email] The contents of the outbox won't show until any ac... r=asuth
Merge pull request #24068 from 6a68/bug-1065632-fxa-fte-reword

Bug 1065632 - Reword FxA description in FTE flow. r=sfoster
Merge pull request #23972 from mikehenrty/bug-1052241-revert-statusbar-setting

Revert "Bug 1052241 - Disable network activity icon in DEBUG mode"