Memory Calculator doesn't recognize max memory value under cgroupsv2

[dmikusa]

What happened?

When running a container built with paketo-buildpacks/java on a system that uses cgroupsv2 and no memory limit is set, then you will see the following message:

WARNING: Unable to convert memory limit "max" from path "/sys/fs/cgroup/memory.max" as int: memory size "max" does not match pattern "^([\\d]+)([kmgtKMGT]?)$"

Followed by...

Calculating JVM memory based on 20801716K available memory

What's happening is that when there is no memory limit set, the literal value in /sys/fs/cgroup/memory.max is max. The buildpack doesn't presently understand this so it tries to parse it as value and fails. That generates the first error.

The buildpack then goes and reads /proc/meminfo, which it does successfully, and picks out the value listed in the message Calculating JVM memory based on....

This generally works out OK because there is no container memory limit set and the memory calculator will essentially use all of the memory on the system. At the same time, the error message is confusing and we can improve the situation.

This PR is for the memory calculator to recognize the option max and use all available memory when that is the case.