Remove the 'expect_out' part of tests spec

In particular the 'test7' case can sometimes take less than 7
nonlinear iterations in parallel because it seems we just start
the Newton solve in a slightly better place after the free power
iterations which results in 4 nonlinear iterations instead of 7

Refs failures on next from #25204

test/tests/executioners/eigen_convergence/tests

@@ -5,15 +5,13 @@
     type = CSVDiff
     csvdiff = 'b_out.csv'
     input = 'b.i'
-    expect_out = '4 Nonlinear'
     absent_out = '5 Nonlinear'
     requirement = 'The system shall be able to solve an eigenvalue problem using something other than the L2 norm of Bx for normalization and a native eigenvalue solver.'
   []
   [test11]
     type = CSVDiff
     csvdiff = 'a_out_eigen_0001.csv'
     input = 'a.i'
-    expect_out = '1[01] Nonlinear'
     absent_out = '12 Nonlinear'
     requirement = 'The system shall be able to solve an eigenvalue problem using the L2 norm of Bx and the sign of its first nonzero entry for normalization with a SLEPc eigenvalue solver.'
   []
@@ -22,7 +20,6 @@
     csvdiff = 'a_out_eigen_0001.csv'
     prereq = test11
     input = 'a.i'
-    expect_out = '7 Nonlinear'
     absent_out = '8 Nonlinear'
     cli_args = 'Problem/bx_norm=fluxintegral'
     petsc_version = '>=3.20.0'
@@ -33,7 +30,6 @@
     csvdiff = 'a_out_eigen_0001.csv'
     prereq = test7
     input = 'a.i'
-    expect_out = '4 Nonlinear'
     absent_out = '5 Nonlinear'
     cli_args = 'Problem/bx_norm=fluxintegral -eps_power_sign_normalization 0'
     petsc_version = '>=3.20.0'