Fix format of deprecated language strings

[jason-platts]

Fixes unit test fail due to format of deprecated.txt

test_validate_deprecated_strings_files with data set #267
lib

core\string_manager_standard_test::test_validate_deprecated_strings_files with data set #267 ('helplinktext,multilang2:viewl...gemenu')
Component name helplinktext,multilang2:viewlanguagemenu appearing in one of the lang/en/deprecated.txt files does not have correct syntax
Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'multilang2:viewlanguagemenu'
+''
/var/www/html/lib/tests/string_manager_standard_test.php:122
/var/www/html/lib/phpunit/classes/advanced_testcase.php:76

[jason-platts]

I've also removed multilang2:viewlanguagemenu as this is not deprecated as the capability still exists, so causes error...
String [multilang2:viewlanguagemenu,tiny_multilang2] is deprecated. Either you should no longer be using that string, or the string has been incorrectly deprecated, in which case you should report this as a bug. Please refer to https://moodledev.io/general/projects/api/string-deprecation
line 395 of /lib/classes/string_manager_standard.php: call to debugging()
line 7009 of /lib/moodlelib.php: call to core_string_manager_standard->get_string()
line 2725 of /lib/accesslib.php: call to get_string()
line 44 of /admin/tool/capability/index.php: call to get_capability_string()