[flang][openacc][NFC] Check only HLFIR lowering for declare tests (#73011)

HLFIR lowering as been set by default now and FIR lowering support will
be removed in the near future. This patch removes the specific FIR check
lines on declare tests.

Author: clementval

flang/test/Lower/OpenACC/acc-declare-globals.f90

@@ -1,7 +1,6 @@
 ! This test checks lowering of OpenACC declare directive in module specification
 ! part.
 
-! RUN: bbc -fopenacc -emit-fir %s -o - | FileCheck %s
 ! RUN: bbc -fopenacc -emit-hlfir %s -o - | FileCheck %s
 
 module acc_declare_test