Enable copy for demo cluster

[leborchuk]

We support special cloud options

		ycmdb.yc_allow_copy_to_program=on
		ycmdb.yc_allow_copy_from_file=on
		ycmdb.yc_allow_copy_to_file=on

They are disabled by default but used in installcheck test suite. Let's enable them for the demo-cluster, which is used in our tests, and on-prem installations can also use them.

Fix test "copy" and maybe some others, not sure wich of them, lets start with test "copy"

Here are some reminders before you submit the pull request

• Add tests for the change
• Document changes
• Communicate in the mailing list if needed
• Pass make installcheck
• Review a PR in return to support the community

[visill]

Is this how it should be?

[leborchuk]

Yep, enabled here by default

[visill]

Then why we use ifeq? Maybe just ENABLE_COPY = true

[robozmey]

Fixes tests:

• float8
• copy
• and some more (at least 5)