tests: do not check all fields of UndefVarError for egal

Refs: JuliaLang/julia#51979

Author: vtjnash

test/distributed_exec.jl

@@ -971,13 +971,15 @@ wid = workers()[1]
     remotecall_fetch(()->T16091, wid)
     false
 catch ex
-    ((ex::RemoteException).captured::CapturedException).ex === UndefVarError(:T16091)
+    ex = ((ex::RemoteException).captured::CapturedException).ex
+    @test (ex::UndefVarError).var === :T16091
 end
 @test try
     remotecall_fetch(identity, wid, T16091)
     false
 catch ex
-    ((ex::RemoteException).captured::CapturedException).ex === UndefVarError(:T16091)
+    ex = ((ex::RemoteException).captured::CapturedException).ex
+    @test (ex::UndefVarError).var === :T16091
 end
 
 f16091a() = 1
@@ -1555,7 +1557,8 @@ try
 catch ex
     @test isa(ex.captured.ex.exceptions[1].ex, ErrorException)
     @test occursin("BoundsError", ex.captured.ex.exceptions[1].ex.msg)
-    @test ex.captured.ex.exceptions[2].ex == UndefVarError(:DontExistOn1)
+    ex = ex.captured.ex.exceptions[2].ex
+    @test (ex::UndefVarError).var === :DontExistOn1
 end
 
 let