oai-pmh update how non-optimal endpoints are shown

Motivation:

Currently, if an endpoint has harvesting suspended then the cell is shown as green, with no indication of any problem. Similarly, when there was a problem, the message is Status: Error, with limited explanation.

Modification:

Remove "Status: Error" as this (in essence) provides no information that isn't already captured by the cell colour.

Update cell colour to show when harvesting was disabled, now shown as an orange cell. This is meant as a kind of half-way between green (=> good) and red (=> bad).

For both cases (error and harvesting disabled) a simple text is provided.

Result:

The output is now better reflects the status of the endpoints.

enabled an automatic merge when all merge checks for e3f28fde pass

merged