Fix recovery-spec test to use only the autoloaded assets in the jobSpec

[busma13]

This PR makes the following changes:

• export the array of e2e autoloaded assets
• Use the array of autoloaded assets in TerasliceHarness.getBaseAssetIds() to get the IDs of autoloaded assets
• Use TerasliceHarness.getBaseAssetIds() in recovery-spec to set the jobSpec.assets array to only the autoloaded assets.

These changes prevent the recovery-spec from trying to use assets placed in the teraslice.assets_directory by other tests running in parallel, that have not finished uploading to ES.
Ref: #3567

[busma13]

This solution works, but I want to look into why we can't just use the array of asset names for jobSpec.assets. The initializeTestExecution calls JobValidator.validateConfig(). The JobValidator uses the OperationLoader which expects asset IDs, not assets names. It seems like jobConfig and ExecutionConfig types might be getting muddled.

[busma13]

I dug into this and here's what I found out:

• OperationLoader uses the asset name it is given as part of the path to the asset.
• JobValidator is used exclusively by the JobsService except for when it is used by tests. JobsService._ensureAssets() converts all jobSpec.assets strings to their IDs using spawnAssetLoader, so validation always passes because the assets are in a subdirectory named as the asset ID.
• recovery-spec is the only test that uses assets from the teraslice.assets_directory. So asset names must be converted to asset IDs so that OperationLoader has the proper path to the assets.
• Any other assets used in tests are in a directory named as the asset name, so the OperationLoader can use the asset name in the asset path to find the information it is looking for.

I think the changes I have made in the PR solve the problem sufficiently.