Revert "hierarchy: regression test for keep cache"

This reverts commit a27378cff8.

tests/various/hierarchy_recursive.v

@@ -1,3 +0,0 @@
-module top(input x, output y);
-top top_i(.x(x), .y(y));
-endmodule

tests/various/hierarchy_recursive.ys

@@ -1,25 +0,0 @@
-read_verilog hierarchy_recursive.v
-hierarchy -auto-top
-select -assert-any top
-select -assert-none a:keep
-
-design -reset
-read_verilog <<EOT
-module top(input x, output y);
-top top_i(.x(x), .y(y));
-always @(x) $display("x=%d", x);
-endmodule
-EOT
-hierarchy -auto-top
-select -assert-any top %% a:keep
-
-design -reset
-read_verilog -formal <<EOT
-module a(input x); b b_i(.x(x)); endmodule
-module b(input x); a a_i(.x(x)); always @(x) assert (x == x); endmodule
-module top(input x); a a_i(.x(x)); endmodule
-EOT
-hierarchy -top top
-select -assert-any a %% a:keep
-select -assert-any b %% a:keep
-select -assert-any top %% a:keep