update images

[bjlittle]

This PR aligns the test_data/images to align with the updates to the imagerepo.json contents given SciTools/iris#4759

Note that, there are two categories of updates.

The following 19 image phashes pre-existed within the test-iris-imagehash repository and require to be copied into this repository for the associated tests:

ec97681793689768943c97e8926669d186e8c33f6c99c32e6b936c83d33e2c98.png -> gallery_tests.test_plot_deriving_phenomena.TestDerivingPhenomena.test_plot_deriving_phenomena.0.png
fa81857e857e7a81857e7a817a81817e7a81857e857e7a81857e7a817a81857e.png -> iris.tests.test_mapping.TestBoundedCube.test_grid.0.png
ea856a95955a954ac17f954a807e3f48951ac07e3e81c0ff7ea16a81c0ff3f81.png -> iris.tests.test_plot.TestMissingCoord.test_no_u.0.png
eafdcec9f4219530b696a56694c3852a95656b7b85986acdc06516adad186e9a.png -> iris.tests.test_plot.TestPlotCoordinatesGiven.test_tx.2.png
eaa9b5699556854e9456854ed05625f9d0a92bfdc0a90afd81f97e00855e7ab6.png -> iris.tests.test_plot.TestPlotCoordinatesGiven.test_tx.4.png
ea856a85954a957ac17e954ac17a9c3e956ac07e3e80c07f3e857aa5c27d3f80.png -> iris.tests.test_plot.TestSimple.test_bounds.0.png
fa856a85957a957ac17e954ac17e1ca2950bc07e3e80c07f3e807a85c1ff3f81.png -> iris.tests.test_plot.TestSimple.test_points.0.png
be813fe0954ac07fc0ff3e81c03fc97a6d0094af3f80c17f36a53240d97f2d82.png -> iris.tests.test_quickplot.TestLabels.test_alignment.0.png
a7fd955a7a016d1a3217c962e4819a56c96f3c859b624d2584de3a6999b662db.png -> iris.tests.test_quickplot.TestLabels.test_contour.0.png
be816a95957a957ac0fe1e8bc07f7f806e01c07f3f80c07f3fa23f00c07f3d00.png -> iris.tests.test_quickplot.TestLabels.test_contourf.0.png
be816a95907ae508c17e955ac07f3fa0945bc07f3f80c07f3aa36f01c0ff3f80.png -> iris.tests.test_quickplot.TestLabels.test_contourf.2.png
eea16affc05ab500956e974ac53f3d80925ac03f2f81c07e3fa12da1c2fe3f80.png -> iris.tests.test_quickplot.TestLabels.test_pcolor.0.png
eea16affc05ab500956e974ac53f3d80925ac03f2f81c07e3fa12da1c2fe3f80.png -> iris.tests.test_quickplot.TestLabels.test_pcolormesh.0.png
ea856a95955a956ac17f950a807e3f4c951ac07e3f81c0ff3ea16aa1c0bd3f81.png -> iris.tests.test_quickplot.TestQuickplotCoordinatesGiven.test_tx.0.png
fa856a85957a957ac17e954ac17e1ca2950bc07e3e80c07f3e807a85c1ff3f81.png -> iris.tests.test_quickplot.TestQuickplotCoordinatesGiven.test_tx.1.png
eafdeec9f729943032168d66d4cb896e9567497b81304aedc96514ad8d18669a.png -> iris.tests.test_quickplot.TestQuickplotCoordinatesGiven.test_tx.2.png
a6fb4b967f00950eb00f9d0f900fcd62dc7868f2c1bb3a909c266e34daa52f6c.png -> iris.tests.test_quickplot.TestQuickplotCoordinatesGiven.test_tx.3.png
eaa9b549f756854ea0168d6ed556896dd8e909ed88290afdd9e97e008d6e2296.png -> iris.tests.test_quickplot.TestQuickplotCoordinatesGiven.test_tx.4.png
aad73e0df78085ac840395ac9428d9fad56cd8f2906c48f2d0ec7a536a1737f3.png -> iris.tests.test_quickplot.TestQuickplotCoordinatesGiven.test_tx.5.png

The following 8 image phashes did not exist within the test-iris-imagehash repository and require to be added into this repository for the associated tests:

iris.tests.test_plot.TestPlotCoordinatesGiven.test_tx.0.png [ea853f10956ac1e3957a854e957a203e955e6aa76ae17aa16a856aaf6ab19e12]
iris.tests.test_plot.TestPlotCoordinatesGiven.test_tx.1.png [ea853a85857a857a957a857a957ed05a857b3e946a606b917a816f247a853af4]
iris.tests.test_plot.TestPlotCoordinatesGiven.test_tx.3.png [aff24ab7fd05952dbd0f950f910fcd48c47868f3e1b9329094266e345a850f6c]
iris.tests.test_plot.TestPlotCoordinatesGiven.test_tx.5.png [eaf73e0d9503852c950395ac9528c1fad06cc0f2d1ec6af2c0fc6a536a1797f3]
iris.tests.test_quickplot.TestLabels.test_contour.1.png [bf802f81c17fc17fc07eb42ac07f3f929130c07e3f81c07f7aa02e85c07f3e81]
iris.tests.test_quickplot.TestLabels.test_contourf.1.png [bf802f81c17fc17fc07eb42ac07f3f929130c07e3f81c07f7aa02e85c07f3e81]
iris.tests.test_quickplot.TestLabels.test_contourf_nameless.0.png [be816af5907ee508c17e955ac03f3f809499c07f3f80c07f3a836f81c0ff3f80]
iris.tests.test_quickplot.TestLabels.test_pcolormesh_str_symbol.0.png [eea16affc05ab500956e974ac53f3d80925ac03f3f80c07e3fa12d21c2ff3f80]