Notest openStringReader multilocale tests (chapel-lang#24453)

Temporarily silence `openStringReader` and `openBytesReader` multilocale
tests to avoid testing noise. These tests, added in
chapel-lang#24323 should be passing in a
multilocale setting and appeared to be when testing the development
branch, but are currently not passing on main.

This PR notest's them to avoid testing noise until the problem can be
resolved. It also reverts the change to the IO module in [this
commit](chapel-lang@77c5e93)
from the same PR in case it has unintended consequences.

- [x] local paratest
- [x] gasnet paratest

[ trivial - not reviewed ]

modules/standard/IO.chpl

@@ -7336,12 +7336,10 @@ proc fileReader.readLine(ref s: string,
       nCodepoints -= 1;
     }
 
-    var sLoc: string;
-
     // now read the data into the string
     // readStringBytesData will advance the fileReader by exactly `nBytes`.
     // This may consume or leave the newline based on the logic above.
-    err = readStringBytesData(sLoc, this._channel_internal, nBytes, nCodepoints);
+    err = readStringBytesData(s, this._channel_internal, nBytes, nCodepoints);
     if foundNewline && stripNewline && !err {
       // pass the newline in the input
       err = qio_channel_read_char(false, this._channel_internal, chr);
@@ -7353,7 +7351,6 @@ proc fileReader.readLine(ref s: string,
 
     // return 'true' if we read anything
     ret = foundNewline || nBytes > 0;
-    s = sLoc;
   }
 
   return ret;
@@ -7424,12 +7421,10 @@ proc fileReader.readLine(ref b: bytes,
       nBytes -= 1;
     }
 
-    var bLoc: bytes;
-
     // now read the data into the bytes
     // readStringBytesData will advance the fileReader by exactly `nBytes`.
     // This may consume or leave the newline based on the logic above.
-    err = readStringBytesData(bLoc, this._channel_internal, nBytes,
+    err = readStringBytesData(b, this._channel_internal, nBytes,
                               nCodepoints=-1);
     if foundNewline && stripNewline && !err {
       // pass the newline in the input
@@ -7445,7 +7440,6 @@ proc fileReader.readLine(ref b: bytes,
 
     // return 'true' if we read anything
     ret = foundNewline || nBytes > 0;
-    b = bLoc;
   }
 
   return ret;