fix main kexi desktop file

Summary:
Fixes lintian errors:

• W: kexi: duplicated-key-in-desktop-entry usr/share/applications/org.kde.kexi-3.1.desktop:69 MimeType
• W: kexi: desktop-mime-but-no-exec-code usr/share/applications/org.kde.kexi-3.1.desktop

Fixes desktop-file-validate errors:

• org.kde.kexi.desktop: error: file contains multiple keys named "MimeType" in group "Desktop Entry"
• org.kde.kexi.desktop: error: value "application/x-kexiproject-sqlite;application/x-kexiproject-shortcut;applicat

ion/x-kexiproject-sqlite3;application/x-sqlite3;application/x-kexi-connectiondata;text/csv;text/tab-separated-va
lues;application/vnd.oasis.opendocument.spreadsheet;application/vnd.oasis.opendocument.text;application/x-msacce
ss;application/vnd.oasis.opendocument.database" for string list key "MimeType" in group "Desktop Entry" does not
have a semicolon (';') as trailing character

• org.kde.kexi.desktop: error: (will be fatal in the future): value "application/x-kexiproject-sqlite,application/

x-kexiproject-shortcut,application/x-kexiproject-sqlite3,application/x-sqlite3,application/x-kexi-connectiondata
,application/x-msaccess;" for key "MimeType" in group "Desktop Entry" contains value "application/x-kexiproject-
sqlite,application/x-kexiproject-shortcut,application/x-kexiproject-sqlite3,application/x-sqlite3,application/x-
kexi-connectiondata,application/x-msaccess" which is an invalid MIME type: "application/x-kexiproject-sqlite,app
lication/x-kexiproject-shortcut,application/x-kexiproject-sqlite3,application/x-sqlite3,application/x-kexi-conne
ctiondata,application/x-msaccess" contains an invalid character in the subtype

Test Plan: Rebuilt the source package with no such errors.

Reviewers: KEXI, staniek

Reviewed By: KEXI, staniek

Subscribers: staniek, KEXI

Tags: KEXI

Differential Revision: https://phabricator.kde.org/D3634