XYZ-110: Cherrypicking changes from release-4.7 to master (#8254)

* Cherry-picking 7b2861de3a to master because enterprise/master has code in it that enterprise/release-4.7 does not, and I don't want enterprise/master to break the next time somebody merges enterprise/release-4.7 to enterprise/master

* Renamed file to match existing scheme

(cherry picked from commit 8c22c5c6c6)

store/sqlstore/upgrade.go

@@ -346,6 +346,8 @@ func UpgradeDatabaseToVersion47(sqlStore SqlStore) {
 	if shouldPerformUpgrade(sqlStore, VERSION_4_6_0, VERSION_4_7_0) {
 		sqlStore.AlterColumnTypeIfExists("Users", "Position", "varchar(128)", "varchar(128)")
 		sqlStore.AlterColumnTypeIfExists("OAuthAuthData", "State", "varchar(1024)", "varchar(1024)")
+		sqlStore.RemoveColumnIfExists("ChannelMemberHistory", "Email")
+		sqlStore.RemoveColumnIfExists("ChannelMemberHistory", "Username")
 		saveSchemaVersion(sqlStore, VERSION_4_7_0)
 	}
 }