Reduce acceptance test sled memory usage

[teor2345]

Motivation

PR #1233 changed the default memory_cache_bytes, but left the
acceptance tests with their old value.

Solution

To avoid similar issues in future, we simply divide the default by 2 just use the default memory limit setting.

Related Issues

Ticket #1026 sled memory usage
PR #1233 default and documentation changes for memory_cache_bytes.

Reviewer

@hdevalence was the author of PR #1233, this PR is a follow-up.
This is a one line change.

This PR is not urgent, unless we are having test memory usage issues.
@dconnolly, you might want to check the memory_cache_bytes setting in the long-running sync tests.

[hdevalence]

Before, we had a reduced memory limit for tests, because the default limit was too large. But now the default is lower. Do we actually want to have the test limit be half of the default limit? Or, could we simply eliminate this setting and use the default, now that we've hopefully fixed the problem that the default limit was too large?

[teor2345]

Before, we had a reduced memory limit for tests, because the default limit was too large. But now the default is lower. Do we actually want to have the test limit be half of the default limit? Or, could we simply eliminate this setting and use the default, now that we've hopefully fixed the problem that the default limit was too large?

The tests run in parallel, so I initially thought we might need a lower memory limit.

But there are actually 2 different types of tests:

• tests that only sync 1 or 1200 blocks - they won't have memory usage issues
• test that sync the whole chain - they need the full memory limit

So I don't think this change is necessary.

[teor2345]

@hdevalence I made a mistake here - we actually need to delete the code that increases the memory limit in the tests, so that the tests just use the default memory limit.

[oxarbitrage]

ACK.