Reduce mem allocations

[vprigent]

As mentioned below, I'm unsure as to what is making the tests fail.

Benchmark:
Using a local projects page firing 42 queries and detecting one include missing:

On 8.0.0

allocated memory by gem
-----------------------------------
   3598454  activesupport-8.0.0.1
   1275662  bullet/lib

Patch:

allocated memory by gem
-----------------------------------
   3598454  activesupport-8.0.0.1
   1139414  bullet/lib

Running the benchmark:

8.0.0

1000 Posts with 10000 Comments and 100 Users       13.591269   0.893714  14.484983 ( 14.682978)

Patch:

1000 Posts with 10000 Comments and 100 Users        6.464706   0.390424   6.855130 (  7.152605)

Which is a surprising improvement, considering I was mostly aiming at reducing the memory usage. I suspect this will actually be more valuable than the 5% memory usage reduction for most people.

Happy for you to review the changes @flyerhzm
I'm not sure how to solve the specs all failing at this time.

I believe there's still a fair bit on the table within the naive implementation for grabbing stack traces, we could for a start limit the size of the stack trace we grab by using caller(0..n) over Thread.current.backtrace or filter straight as we grab the content of the backtrace might do the trick too?

[vprigent]

microbenchmark on sub showed rindex is about twice as fast for this sort of work.
memoizing here is just the cherry on top

[vprigent]

I haven't changed anything relevant to the CI and each failed job seems to relate to a CI change rather than the code changes here... Not sure what's up with that.

[flyerhzm]

@vprigent great job on performance tuning, thank you, I'll merge it and fix the CI.