[Aarch64/FFI] Remove static from arrangeDowncall() & arrangeUpcall()

[ChengJin01]

The changes remove the static keyword from arrangeDowncall()
and arrangeUpcall() in CallArranger to adapt to the existing setting
in OpenJDK intended for Aarch64.

Signed-off-by: ChengJin01 jincheng@ca.ibm.com

[ChengJin01]

As explained at ibmruntimes/openj9-openjdk-jdk20#12 (comment) plus the response from Oracle at https://mail.openjdk.org/pipermail/panama-dev/2023-February/018496.html

The AArch64 CallArranger has several different subclasses (for different OSes). 
The arrangeDowncall/arrangeUpcall method calls (indirectly through getBindings)
several overridden instance methods in these  subclasses (see the `abstract` methods
in the AArch64 CallArranger), so  it has to be non-static.

For the x64 implementations of CallArranger we don't have any subclasses 
of CallArranger, so there the method can be static.

we should follow the existing pattern in OpenJDK as they refactored their FFI framework with static removed from these two methods in CallArranger on Aarch64 since JDK18, given we already removed them in JDK20 at ibmruntimes/openj9-openjdk-jdk20#12.

Note: there is no change required in OpenJ9 as everything is already set up correctly in there to deal with the case. That being said, their work on Aarch64 has no impact on our code in OpenJ9 at this point.

[ChengJin01]

The tiny changes are verified in personal builds on Aarch64 with all FFI test suites passed.

Reviewer: @tajila
FYI: @pshipton

[tajila]

jenkins test sanity alinux64 jdk19