do not special case JVMCI in tiered compilation policy

There is some Graal specific code in the tiered compilation policy[1] that should be removed so that Graal benefits from the same feedback-based compilation queue management as C2. The problem described in the comment for this code has mostly likely been fixed by now and even if not, this is something that should be fixed in Graal, not worked around in JVMCI.

[1] https://github.com/openjdk/jdk/blob/977a21add8d275dae802a769e6c63675a8ec3ea9/src/hotspot/share/compiler/compilationPolicy.cpp#L1057-L1069