[FLASK] Remove long-running Snap permission (#20951)

## **Description**
This PR removes `long-running` Snap endowment/permission.

Snaps team have decided to remove this endowment because of its
unpredictable security concerns around running Snaps indefinitely. This
endowment is removed in favor of the new endowments that will be focused
on solving certain use cases that require snap to be running for more
time than default.

## **Related issues**

_Fixes [#945](MetaMask/snaps#945

## **Related PR**
MetaMask/snaps#1751 (**required**)
MetaMask/metamask-docs#919

## **Pre-merge author checklist**

- [ ] I’ve followed [MetaMask Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've clearly explained:
  - [ ] What problem this PR is solving.
  - [ ] How this problem was solved.
  - [ ] How reviewers can test my changes.
- [ ] I’ve indicated what issue this PR is linked to: Fixes #???
- [ ] I’ve included tests if applicable.
- [ ] I’ve documented any added code.
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
- [ ] I’ve properly set the pull request status:
  - [ ] In case it's not yet "ready for review", I've set it to "draft".
- [ ] In case it's "ready for review", I've changed it from "draft" to
"non-draft".

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

shared/constants/permissions.test.js

@@ -12,7 +12,6 @@ describe('EndowmentPermissions', () => {
     // test, so we re-add them here.
     expect(Object.keys(EndowmentPermissions).sort()).toStrictEqual(
       [
-        'endowment:long-running',
         'endowment:lifecycle-hooks',
         'endowment:name-lookup',
         ...Object.keys(endowmentPermissionBuilders).filter(

shared/constants/snaps/permissions.ts

@@ -6,7 +6,6 @@ export const EndowmentPermissions = Object.freeze({
   'endowment:rpc': 'endowment:rpc',
   'endowment:webassembly': 'endowment:webassembly',
   ///: BEGIN:ONLY_INCLUDE_IN(build-flask)
-  'endowment:long-running': 'endowment:long-running',
   'endowment:lifecycle-hooks': 'endowment:lifecycle-hooks',
   'endowment:name-lookup': 'endowment:name-lookup',
   ///: END:ONLY_INCLUDE_IN
@@ -32,8 +31,6 @@ export const ExcludedSnapEndowments = Object.freeze({
   ///: BEGIN:ONLY_INCLUDE_IN(build-main)
   'endowment:keyring':
     'This endowment is still in development therefore not available.',
-  'endowment:long-running':
-    'endowment:long-running is deprecated. For more information please see https://github.com/MetaMask/snaps/issues/945.',
   'endowment:lifecycle-hooks':
     'This endowment is experimental and therefore not available.',
   ///: END:ONLY_INCLUDE_IN

ui/helpers/utils/permission.js

@@ -314,12 +314,6 @@ export const PERMISSION_DESCRIPTIONS = deepFreeze({
     rightIcon: null,
     weight: 2,
   }),
-  [EndowmentPermissions['endowment:long-running']]: ({ t }) => ({
-    label: t('permission_longRunning'),
-    description: t('permission_longRunningDescription'),
-    leftIcon: IconName.Link,
-    weight: 3,
-  }),
   [EndowmentPermissions['endowment:transaction-insight']]: ({
     t,
     permissionValue,