Remove register_attr-related tests

Signed-off-by: Yuki Okushi <[email protected]>

Author: JohnTitor

src/test/ui-fulldeps/issue-15778-pass.rs

@@ -1,3 +1,4 @@
+// gate-test-custom_inner_attributes
 // compile-flags: -Z span-debug --error-format human
 // aux-build:test-macros.rs
 // edition:2018

src/test/ui-fulldeps/issue-15778-pass.stderr

@@ -1,23 +1,23 @@
 error: expected non-macro inner attribute, found attribute macro `print_attr`
-  --> $DIR/inner-attrs.rs:63:12
+  --> $DIR/inner-attrs.rs:64:12
    |
 LL |         #![print_attr]
    |            ^^^^^^^^^^ not a non-macro inner attribute
 
 error: expected non-macro inner attribute, found attribute macro `print_attr`
-  --> $DIR/inner-attrs.rs:67:12
+  --> $DIR/inner-attrs.rs:68:12
    |
 LL |         #![print_attr]
    |            ^^^^^^^^^^ not a non-macro inner attribute
 
 error: expected non-macro inner attribute, found attribute macro `print_attr`
-  --> $DIR/inner-attrs.rs:71:12
+  --> $DIR/inner-attrs.rs:72:12
    |
 LL |         #![print_attr]
    |            ^^^^^^^^^^ not a non-macro inner attribute
 
 error: expected non-macro inner attribute, found attribute macro `print_attr`
-  --> $DIR/inner-attrs.rs:75:12
+  --> $DIR/inner-attrs.rs:76:12
    |
 LL |         #![print_attr]
    |            ^^^^^^^^^^ not a non-macro inner attribute