Removes deprecated {.injectStmt.}. Fixes #18666 (#18984)

tests/pragmas/tinjectstmt.nim

@@ -1,51 +0,0 @@
-discard """
-  joinable: false
-  output:'''
-onInject: 1
-onInject: 2
-ok0
-ok1
-onInject: 3
-onInject: 4
-onInject: 5
-0
-onInject: 6
-onInject: 7
-onInject: 8
-1
-onInject: 9
-onInject: 10
-onInject: 11
-2
-ok2
-onInject: 12
-'''
-"""
-
-# test {.injectStmt.}
-
-#[
-{.injectStmt.} pragma can be used to inject a statement before every
-other statement in the current module. It's now undocumented and may be removed
-in the future and replaced with something more general and without its limitations.
-(e.g. doesn't work in VM or js backends).
-]#
-
-from system/ansi_c import c_printf
-
-var count = 0
-proc onInject*() =
-  count.inc
-  # echo count # xxx would fail, probably infinite recursion
-  c_printf("onInject: %d\n", cast[int](count))
-
-{.injectStmt: onInject().}
-echo "ok0"
-proc main()=
-  echo "ok1"
-  for a in 0..<3:
-    echo a
-  echo "ok2"
-
-static: main() # xxx injectStmt not honored in VM
-main()