Suppress color bar for constant order plot

[delucchi-cmu]

Suppresses the color bar legend if the pixel list contains only one healpix Norder.

Using the healpy.visufunc.mollview method, we don't have a lot of control over the color bar tick marks. The under-construction healpy.newvisufunc.projview method makes this problem easier, but does not yet support masking (e.g. the gray background for areas where there is no catalog coverage).

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.19%. Comparing base (005d780) to head (ccd953f).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #267 +/- ## ======================================= Coverage 94.19% 94.19% ======================================= Files 55 55 Lines 1928 1929 +1 ======================================= + Hits 1816 1817 +1 Misses 112 112 ```

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[github-actions[bot]]

Before [005d780d]	After [95bb5817]	Ratio	Benchmark (Parameter)
19.7±0.5ms	19.6±0.8ms	1	benchmarks.MetadataSuite.time_load_partition_info_order6
77.5±0.1ms	77.3±0.9ms	1	benchmarks.MetadataSuite.time_load_partition_join_info
364±2ms	363±3ms	1	benchmarks.Suite.time_outer_pixel_alignment
77.8±0.6ms	76.9±1ms	0.99	benchmarks.MetadataSuite.time_load_partition_info_order7
124±0.6ms	123±2ms	0.99	benchmarks.time_test_alignment_even_sky
13.5±0.06ms	13.4±0.2ms	0.99	benchmarks.time_test_cone_filter_multiple_order
41.1±0.8ms	40.4±1ms	0.98	benchmarks.Suite.time_pixel_tree_creation
13.3±0.2ms	13.0±0.1ms	0.97	benchmarks.Suite.time_inner_pixel_alignment
88.2±3ms	85.1±3ms	0.96	benchmarks.Suite.time_paths_creation

Click here to view all benchmarks.