fix(tests): read the work location from _SASJS_WORK

@sasjs/core 6.0.0 renamed the session globals to a _SASJS_ prefix and sets
_SASJS_WORK only; SASJSWORK no longer exists (and sasjs/server's pre-program
compat aliases never covered it). testsetup.sas still read &sasjswork in both
the SASJS and SASMETA arms of %update_settings, so under the new pin those
filename statements built unrooted paths and ms_createfile / mm_createstp wrote
outside the session work directory, breaking sasjs test setup on SASJS and SAS9.

mp_init() is called at the top of the script, so _SASJS_WORK is defined here.

sas/sasjs/tests/testsetup.sas

@@ -192,7 +192,7 @@ options mprint;
 %else %if &pf=SASJS %then %do;
   %mx_getcode(&root/services/public/settings,outref=stngs)
 
-  filename sendback "&sasjswork/settings2.txt" lrecl=1000;
+  filename sendback "&_SASJS_WORK/settings2.txt" lrecl=1000;
   data _null_;
     file sendback;
     infile stngs end=last lrecl=1000;
@@ -223,11 +223,11 @@ options mprint;
 
   %mm_getstpcode(tree=&root/services/public
     ,name=Data_Controller_Settings
-    ,outloc=&sasjswork/settings.txt
+    ,outloc=&_SASJS_WORK/settings.txt
   )
   data _null_;
-    file "&sasjswork/settings2.txt";
-    infile "&sasjswork/settings.txt" end=last;
+    file "&_SASJS_WORK/settings2.txt";
+    infile "&_SASJS_WORK/settings.txt" end=last;
     input;
     put _infile_;
     if last then do;
@@ -238,7 +238,7 @@ options mprint;
   %mm_deletestp(target=&root/services/public/Data_Controller_Settings)
   %mm_createstp(stpname=Data_Controller_Settings
     ,filename=settings2.txt
-    ,directory=&sasjswork
+    ,directory=&_SASJS_WORK
     ,tree=&root/services/public
     ,Server=SASApp
     ,stptype=2