I always use rpm to update packages and never had any problem.
In my opinion the package is corrupted.
The same package from the SP3 stack works. The other packages are hydentical, but apache2-utils in SP4 is smaller than in SP3.

== SUSE Linux Enterprise Server 12 SP3 ==

Code:
$ md5sum *
cd9f63a3b1407d8ec7e7b70a9c2d185e  apache2-2.4.23-29.34.4.x86_64.rpm
c28c2707477c7d1a4f0eaacb2d6b3095  apache2-devel-2.4.23-29.34.4.x86_64.rpm
3d6dcfef932b789204a1bf211dcb9209  apache2-prefork-2.4.23-29.34.4.x86_64.rpm
53a8c06219a586a1ce267ce3c02be03e  apache2-utils-2.4.23-29.34.4.x86_64.rpm
$ stat -c "%s %n" *
1199425 apache2-2.4.23-29.34.4.x86_64.rpm
248428 apache2-devel-2.4.23-29.34.4.x86_64.rpm
291673 apache2-prefork-2.4.23-29.34.4.x86_64.rpm
146091 apache2-utils-2.4.23-29.34.4.x86_64.rpm
== SUSE Linux Enterprise Server 12 SP4 ==

Code:
$ md5sum *
cd9f63a3b1407d8ec7e7b70a9c2d185e  apache2-2.4.23-29.34.4.x86_64.rpm
c28c2707477c7d1a4f0eaacb2d6b3095  apache2-devel-2.4.23-29.34.4.x86_64.rpm
3d6dcfef932b789204a1bf211dcb9209  apache2-prefork-2.4.23-29.34.4.x86_64.rpm
d63fd1917cb1cdb8ee90d9055ddd9e0f  apache2-utils-2.4.23-29.34.4.x86_64.rpm
$ stat -c "%s %n" *
1199425 apache2-2.4.23-29.34.4.x86_64.rpm
248428 apache2-devel-2.4.23-29.34.4.x86_64.rpm
291673 apache2-prefork-2.4.23-29.34.4.x86_64.rpm
121856 apache2-utils-2.4.23-29.34.4.x86_64.rpm