[submodule update] sonic-sairedis to move to SAI1.8.1 (sonic-net#7393)

What/Why I did:

Updated sonic-sairedis submodule to use SAI1.8.1
[Submodule update] sonic-sairedis
d821bc0 (HEAD -> master, origin/master, origin/HEAD) [Mellanox] Add SAI template 
config support (sonic-net#803)
bb341e9 [syncd] Bring back TimerWatchdog (sonic-net#821)
badf6ce Update .gitignore (sonic-net#822)
1494bc6 [meta] Mark local function static (sonic-net#818)
34e961c [pyext] Fix pyext/py2 library (sonic-net#820)
0d3749d Moved SAI Header to git tag v1.8.1 (sonic-net#816)
70fff78 Added --purge of base docker image packages before installing new ones. (sonic-net#819)

Updated Broadcom SAI Debian package to 4.3.3.4-2 to use SAI 1.8.1 Header

platform/broadcom/sai.mk

@@ -1,8 +1,8 @@
-BRCM_SAI = libsaibcm_4.3.3.4-1_amd64.deb
-$(BRCM_SAI)_URL = "https://sonicstorage.blob.core.windows.net/packages/bcmsai/4.3/master/libsaibcm_4.3.3.4-1_amd64.deb?sv=2019-12-12&st=2021-04-16T16%3A07%3A16Z&se=2030-04-17T16%3A07%3A00Z&sr=b&sp=r&sig=BiY2sN%2FVvDzZlxPEGWMwMLeB725yCvwrORHULdnWyXU%3D"
-BRCM_SAI_DEV = libsaibcm-dev_4.3.3.4-1_amd64.deb
+BRCM_SAI = libsaibcm_4.3.3.4-2_amd64.deb
+$(BRCM_SAI)_URL = "https://sonicstorage.blob.core.windows.net/packages/bcmsai/4.3/master/libsaibcm_4.3.3.4-2_amd64.deb?sv=2015-04-05&sr=b&sig=DuX9sPYncs6MySLYMFOVSIxHvaBUn%2FJaeokJi9nVUb0%3D&se=2024-01-16T14%3A30%3A20Z&sp=r"
+BRCM_SAI_DEV = libsaibcm-dev_4.3.3.4-2_amd64.deb
 $(eval $(call add_derived_package,$(BRCM_SAI),$(BRCM_SAI_DEV)))
-$(BRCM_SAI_DEV)_URL = "https://sonicstorage.blob.core.windows.net/packages/bcmsai/4.3/master/libsaibcm-dev_4.3.3.4-1_amd64.deb?sv=2019-12-12&st=2021-04-16T16%3A07%3A55Z&se=2030-04-17T16%3A07%3A00Z&sr=b&sp=r&sig=XVNsLj8QwhGN3sgvgvPZ2glnLZm9Dhyci%2F61k36Fl0c%3D"
+$(BRCM_SAI_DEV)_URL = "https://sonicstorage.blob.core.windows.net/packages/bcmsai/4.3/master/libsaibcm-dev_4.3.3.4-2_amd64.deb?sv=2015-04-05&sr=b&sig=CqqazugaYvhUgsW2CkDvgJljTJL8tFT3WcDAlkIxjdY%3D&se=2024-01-16T14%3A31%3A19Z&sp=r"
 
 SONIC_ONLINE_DEBS += $(BRCM_SAI)
 $(BRCM_SAI_DEV)_DEPENDS += $(BRCM_SAI)