Remove zero arg methods of + and * from linalg tests (#56184)

There are tests elsewhere that i) make sure there is no zero-arg methods
of these functions and ii) tests that e.g. `+()` throws a `MethodError`.
Without this patch there are test errors whenever the same test process
runs both of these tests.

(cherry picked from commit f5937b432c51f6b8a5b28eaa5c1583f1350e12a3)
(cherry picked from commit cf965f3a6f52ed84c71e4f95010bbbe422741d8e)

Author: fredrikekre

test/matmul.jl

@@ -1116,8 +1116,8 @@ end
     Base.zero(::Thing)       = Thing(0.)
     Base.one(::Type{Thing})  = Thing(1.)
     Base.one(::Thing)        = Thing(1.)
-    Base.:+(t::Thing...)     = +(getfield.(t, :data)...)
-    Base.:*(t::Thing...)     = *(getfield.(t, :data)...)
+    Base.:+(t1::Thing, t::Thing...) = +(getfield.((t1, t...), :data)...)
+    Base.:*(t1::Thing, t::Thing...) = *(getfield.((t1, t...), :data)...)
 
     M = Float64[1 2; 3 4]
     A = Thing.(M)