fix sqlite transactions

[arnauds5]

• Add a missing defer tx.Rollback
• Change some s.database.Exec(...) into tx.Exec(...) if it there is a transaction
• Change unprocessed message sql query from "insert ..." to "insert or ignore ..." so that duplicate message doesn't block all the others messages to be handled

[github-actions[bot]]

Pull reviewers stats

Stats of the last 30 days for popstellar:		User	Total reviews	Time to review	Total comments
	K1li4nL 🥇	23 ▀▀▀▀	8h 33m))	12 ▀▀
	matteosz 🥈	9 ▀	2d 1h 15m)) ▀	22 ▀▀▀
	arnauds5 🥉	7 ▀	4h 29m))	4 ▀
	emonnin-epfl	6 ▀	8h 20m))	8 ▀
	sgueissa	4 ▀	1h 25m))	7 ▀
	onsriahi14	3	1d 10h 51m)) ▀	4 ▀
	quadcopterman	3	10d 7h 3m)) ▀▀▀▀	1
	1florentin	2	10d 5h 50m)) ▀▀▀▀	0
	MariemBaccari	2	22h 39m))	6 ▀
	Kaz-ookid	2	2d 4h 12m)) ▀	9 ▀
	simone-kalbermatter	1	9h 17m))	0

^{⚡️ Pull request stats}

[sonarcloud[bot]]

Quality Gate passed for 'PoP - PoPCHA-Web-Client'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud[bot]]

Quality Gate passed for 'PoP - Be2-Scala'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud[bot]]

Quality Gate passed for 'PoP - Be1-Go'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarcloud[bot]]

Quality Gate passed for 'PoP - Fe2-Android'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud