Removing FilesSearch feature flag (#17548)

* Removing FilesSearch feature flag

* Fixing tests

* Adding an improvement on plain text extraction

* Adding tests for plain text extraction

* Removed unneeded conversion

* Adding missed license

* Remove the feature flag from the migration

* Fixing some tests

* Updating i18n/en.json file

app/file.go

@@ -782,7 +782,7 @@ func (a *App) UploadFileX(channelID, name string, input io.Reader,
 		}
 	}
 
-	if *a.Config().FileSettings.ExtractContent && a.Config().FeatureFlags.FilesSearch {
+	if *a.Config().FileSettings.ExtractContent {
 		infoCopy := *t.fileinfo
 		a.Srv().Go(func() {
 			err := a.ExtractContentFromFileInfo(&infoCopy)
@@ -1040,7 +1040,7 @@ func (a *App) DoUploadFileExpectModification(now time.Time, rawTeamId string, ra
 		}
 	}
 
-	if *a.Config().FileSettings.ExtractContent && a.Config().FeatureFlags.FilesSearch {
+	if *a.Config().FileSettings.ExtractContent {
 		infoCopy := *info
 		a.Srv().Go(func() {
 			err := a.ExtractContentFromFileInfo(&infoCopy)

app/migrations.go

@@ -288,9 +288,6 @@ func (a *App) DoSystemConsoleRolesCreationMigration() {
 }
 
 func (a *App) doContentExtractionConfigDefaultTrueMigration() {
-	if !a.Config().FeatureFlags.FilesSearch {
-		return
-	}
 	// If the migration is already marked as completed, don't do it again.
 	if _, err := a.Srv().Store.System().GetByName(ContentExtractionConfigDefaultTrueMigrationKey); err == nil {
 		return

app/post_metadata_test.go

@@ -177,6 +177,7 @@ func TestPreparePostForClient(t *testing.T) {
 		defer th.TearDown()
 
 		fileInfo, err := th.App.DoUploadFile(time.Now(), th.BasicTeam.Id, th.BasicChannel.Id, th.BasicUser.Id, "test.txt", []byte("test"))
+		fileInfo.Content = "test"
 		require.Nil(t, err)
 
 		post, err := th.App.CreatePost(&model.Post{

app/upload.go

@@ -299,7 +299,7 @@ func (a *App) UploadData(us *model.UploadSession, rd io.Reader) (*model.FileInfo
 		}
 	}
 
-	if *a.Config().FileSettings.ExtractContent && a.Config().FeatureFlags.FilesSearch {
+	if *a.Config().FileSettings.ExtractContent {
 		infoCopy := *info
 		a.Srv().Go(func() {
 			err := a.ExtractContentFromFileInfo(&infoCopy)