Fix syntax errors in some pre-removal and post-installation scripts

[keryell]

This was introduced with commit 2b870279f68f7f2b3d08315b7269acbdc1c6033c from https://github.com/Xilinx/XRT/pull/8008

[keryell]

Probably the CI does not look at install script execution? Or some systems have bash as sh?

[keryell]

OK, the problem seems worse. It looks like the CI is probably broken since https://github.com/Xilinx/XRT/pull/7835 @zhangchiming It is unclear how it is possible.

[keryell]

There is still a failing XRT test https://github.com/Xilinx/XRT/actions/runs/8531822644/job/23372394605?pr=8046 pcie-hw-tests (xilinx_u250_gen3x16_xdma_4_1_202210_1) with http://fisweb:8080/proj/fis/scripts/buildNumber:571_1_boardfarm_xilinx_u250_gen3x16_xdma_4_1_202210_1.log

2024-04-02 18:47:21,458 - root - INFO - b'2024.04.02.18.47.21 INFO: ERROR: Post-check FAILED : [Install_XRT] : XRT did not compile drivers on xcosdae368\n'
1021	2024-04-02 18:47:21,463 - root - INFO - b'2024.04.02.18.47.21 INFO: ERROR: ERROR: Failed to run step Install_XRT in Main flow pipeline_2rp_no_xrm: XRT did not compile drivers on xcosdae368\n'

I do not have access to the compilation logs because I cannot log into the machine (the ssh hangs forever). I am also concerned by this machine using Linux 4.18 from 2018. :frowning_face:

[keryell]

Rebased on master to see whether it fixes the CI.

[keryell]

@sonals @stsoe Do you have a plan to make progress on this?

[keryell]

Rebasing on master after 2 weeks to see whether it fixes the CI.

[stsoe]

@keryell Can you rebase and force push? Seems like there is no way to restart CI for this old PR.

[keryell]

The CI looks broken: it accepted some bugs in the past and trying to remove them breaks the CI??? :thinking: