Remove Secure Backup, Cross-signing and Cryptography sections in Security & Privacy user settings (#29088)

* feat(security tab)!: remove secure backup panel

BREAKING CHANGE: the key storage user interaction are moved into the Encryption tab. The debugging information are moved into the devtools.

* feat(security tab)!: remove cross signing section

BREAKING CHANGE: the cryptographic identity can be reseted in the Encryption tab. The debugging information are moved into the devtools

* feat(security tab)!: remove cryptography section

BREAKING CHANGE: this section can be found in the Advanced section of the encryption tab.

* test(security tab): update snapshot

* chore(security tab): remove unused component and function

* chore(security tab): update i18n

* test(e2e): remove `backups.spec.ts`

res/css/_components.pcss

@@ -340,8 +340,6 @@
 @import "./views/rooms/wysiwyg_composer/components/_FormattingButtons.pcss";
 @import "./views/rooms/wysiwyg_composer/components/_LinkModal.pcss";
 @import "./views/settings/_AvatarSetting.pcss";
-@import "./views/settings/_CrossSigningPanel.pcss";
-@import "./views/settings/_CryptographyPanel.pcss";
 @import "./views/settings/_FontScalingPanel.pcss";
 @import "./views/settings/_ImageSizePanel.pcss";
 @import "./views/settings/_IntegrationManager.pcss";
@@ -354,7 +352,6 @@
 @import "./views/settings/_PhoneNumbers.pcss";
 @import "./views/settings/_PowerLevelSelector.pcss";
 @import "./views/settings/_RoomProfileSettings.pcss";
-@import "./views/settings/_SecureBackupPanel.pcss";
 @import "./views/settings/_SetIntegrationManager.pcss";
 @import "./views/settings/_SettingsFieldset.pcss";
 @import "./views/settings/_SettingsHeader.pcss";