REGTEST: Fix format of set-uri HTTP request rule in h1or2_to_h1c.vtc

First, concat() is a converter, not a sample fetch. So use str() sample fetch
with no string and call concat on it. Then, the argument of the set-uri rule
must be a log format string. So it must be inside %[] to be evaluated.
diff --git a/reg-tests/http-rules/h1or2_to_h1c.vtc b/reg-tests/http-rules/h1or2_to_h1c.vtc
index 0ed0984..3fbc3f7 100644
--- a/reg-tests/http-rules/h1or2_to_h1c.vtc
+++ b/reg-tests/http-rules/h1or2_to_h1c.vtc
@@ -57,7 +57,7 @@
 	http-request set-header     sl1      "sl1: "
 
 	http-request set-method              "%[str(GET)]"
-	http-request set-uri                 concat(/bu/,req.uri,/eu)
+	http-request set-uri                 %[str(),concat(/bu/,req.uri,/eu)]
 	http-request set-path                "/bp/%[var(req.path)]/ep"
 	http-request set-query               "bq&%[var(req.query)]&eq"
 
@@ -124,7 +124,7 @@
 	http-request set-header     sl1      "sl1: "
 
 	http-request set-method              "%[str(GET)]"
-	http-request set-uri                 concat(/bu/,req.uri,/eu)
+	http-request set-uri                 %[str(),concat(/bu/,req.uri,/eu)]
 	http-request set-path                "/bp/%[var(req.path)]/ep"
 	http-request set-query               "bq&%[var(req.query)]&eq"