Updates for cloud Data Export and migration pipelines.

[eiffel777]

This PR fixes three issues.

1. Using the correct table for the time field in the JobDataset.php file. The session_records table has the start_time_ts and end_time_ts columns that should be used for the start time and end time parameters. It was trying to use the instance table which does not have those columns.
2. Changing the host table to have a single autoincrement column instead of a composite autoincrement. In PR Change account, instance and instance_type tables to have single unique auto increment column #1263 we changed most of the cloud realm dimension tables that use a composite autoincrement key to use a single unique column for the autoincrement key. At the time the host table was not used for anything so it was not converted. It is now being used in the cloud instance viewer and Data Export and should be changed to match the other cloud realm dimension tables so it can provide accurate data. The changes for the host table match changes made for the instance, account, and instance_type tables in PR Change account, instance and instance_type tables to have single unique auto increment column #1263 and changing account, instance and instance_type tables to have global un… #1272 including a SQL statement that is run during the migration to add the new autoincrement key and update rows in the event table with the appropriate host_id.
3. Renaming the cloud migration pipelines so they are not automatically run. Having the cloud migration pipelines with migration-9_0_0-9_5_0 in them meant they automatically ran. We do not want that as not all XDMoD installations may be using the cloud realm.

Tests performed

Tested fresh install and upgrade in docker

Checklist:

• The pull request description is suitable for a Changelog entry
• The milestone is set correctly on the pull request
• The appropriate labels have been added to the pull request

[jtpalmer]

I'm assuming this is unrelated, but thought I would mention it here while I was checking this:

2021-04-21 18:20:16 [notice] Altering table `modw_cloud`.`session_records`
2021-04-21 18:20:16 [warning] SQL warnings on table '`modw_cloud`.`session_records`' generated by action xdmod.cloud-migration-9-0-0_9-5-0.cloud-session-records
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null
2021-04-21 18:20:16 [warning] Warning 1048 Column 'memorybucket_id' cannot be null