updated dockerfile to use ubi image

[austinmartinh]

The alpine image being used in the dockerfile was being replaced when built, meaning the apk upgrade command failed. The Dockerfile has been updated to fix this.

Verification:

• Clone this repo
• Build image from dockerfile
• verify build succeeds

[davidkirwan]

$ make image/build
INFO[0000] Building OCI image quay.io/integreatly/application-monitoring-operator:1.1.4 
STEP 1: FROM registry.access.redhat.com/ubi7/ubi-minimal:latest
Getting image source signatures
Copying blob 59c95d971453 done  
Copying blob 3f6f22a01d7d done  
Copying config 082938f7ed done  
Writing manifest to image destination
Storing signatures
STEP 2: USER nobody
39391a634f73a654ebed805a0664303ed3b3bf896b23a2953366c49df5308c52
STEP 3: ADD templates /usr/local/bin/templates/
7a5766f50670053f9fb391740a3c7085e9cc67f700e500378e48dd24abfc3118
STEP 4: ADD build/_output/bin/application-monitoring-operator /usr/local/bin/application-monitoring-operator
STEP 5: COMMIT quay.io/integreatly/application-monitoring-operator:1.1.4
0bf8c74f3b142a3c480ac1106a4401a9a19ed51de2bd207e97c5b3411a0f3614
0bf8c74f3b142a3c480ac1106a4401a9a19ed51de2bd207e97c5b3411a0f3614
INFO[0013] Operator build complete.                     
$ docker images
REPOSITORY                                            TAG      IMAGE ID       CREATED          SIZE
quay.io/integreatly/application-monitoring-operator   1.1.4    0bf8c74f3b14   19 seconds ago   123 MB
registry.access.redhat.com/ubi7/ubi-minimal           latest   082938f7edb4   5 weeks ago      83 MB