tree-switch-conversion: don't apply switch size limit on jump tables

commit 56946c80 ("gimple: Add limit after which slower switchlower
algs are used [PR117091] [PR117352]") introduced a limit on the number
of cases of a switch. It also bails out on finding jump tables if the
switch is too large. This introduces a compile time regression during
bootstrap. A riscv bootstrap takes hours longer. Particularly
insn-attrtab.cc will take hours instead of minutes. Fix this by not
applying the switch size limit on jump tables.

An alternative would be to implement greedy switch clustering for jump
tables as is done for switch bitmap clustering.

gcc/ChangeLog:

	PR tree-optimization/118032
	* tree-switch-conversion.cc (jump_table_cluster::find_jump_tables):
	Remove param_switch_lower_slow_alg_max_cases check.