Handle trove service availabilty in tempest.

Partially implements blueprint: trove-tempest
Change-Id: I5413a7afeffe670f6972b41d61dd27ed05da5ba2
bash8: fix bash8 warning

This patch removes the following bash8 warnings.

> /devstack/ $ ./run_tests.sh
> Running bash8...
> E003: Indent not multiple of 4: '             wget -c $image_url -O $FILES/$IMAGE_FNAME'
>  - functions: L1367
> E003: Indent not multiple of 4: '             if [[ $? -ne 0 ]]; then'
>  - functions: L1368
> E003: Indent not multiple of 4: '                 echo "Not found: $image_url"'
>  - functions: L1369
> E003: Indent not multiple of 4: '                 return'
>  - functions: L1370
> E003: Indent not multiple of 4: '             fi'
>  - functions: L1371
> E003: Indent not multiple of 4: '                                 `"should use a descriptor-data pair."'
>  - functions: L1423
> E003: Indent not multiple of 4: '                         `" Attempt to retrieve the *-flat.vmdk: $flat_url"'
>  - functions: L1438
> E003: Indent not multiple of 4: '                             `" Attempt to retrieve the descriptor *.vmdk: $descriptor_url"'
>  - functions: L1477
> E003: Indent not multiple of 4: '                         warn $LINENO "Descriptor not found $descriptor_url"'
>  - functions: L1492
> E003: Indent not multiple of 4: '                         descriptor_found=false'
>  - functions: L1493
> E003: Indent not multiple of 4: '                 fi'
>  - functions: L1501
> E003: Indent not multiple of 4: '             fi'
>  - functions: L1502
> E003: Indent not multiple of 4: '             #TODO(alegendre): handle streamOptimized once supported by the VMware driver.'
>  - functions: L1503
> E003: Indent not multiple of 4: '             vmdk_disktype="preallocated"'
>  - functions: L1504
> 14 bash8 error(s) found

Change-Id: Icf2cddf283192a50253ccfa697c2d32eec75b4ba
Closes-Bug: #1267716
Merge "bash8: fix bash8 warning"
Merge "Handle trove service availabilty in tempest."