remove temporary landFilenames from test/em_real (#1424)

TYPE: no impact

KEYWORDS: remove 

SOURCE: internal

DESCRIPTION OF CHANGES:
There is a file in the test/em_real directory that does not belong in the repository: landFilenames.

The `landFilenames` has a storied history:
```
commit 7629cd0
Author: John Michalakes <[email protected]>
Date:   Fri Feb 18 18:55:16 2005 +0000
    Temporary addition for hires topo input. Should remove later. JM
    git-svn-id: https://svn-wrf-model.cgd.ucar.edu/trunk@753 b0b5d27b-6f0f-0410-a2a3-cb1e977edc3d
```
John's advice was to "remove later". We waited 16 years, and now we are removing the file.


LIST OF MODIFIED FILES:
D    test/em_real/landFilenames

TESTS CONDUCTED: 
1. Jenkins is OK.